Issued December 16, 1910. U. S. DEPARTMENT OF AGRICULTURE. BUREAU OF SOILS— MILTON WHITNEY, Chief. IN COOPERATION WITH THE UNIVERSITY OF CALIFORNIA, AGRICULTURAL EXPERIMENT STATION, THOMAS F. HUNT, DIRECTOR; CHARLES F. SHAW, IN CHARGE SOIL SURVEY. SOIL SURVEY GF THE UKIAH AREA, CALIFORNIA. BY E. B. WATSON, OF the U. S. Department of Agriculture, in Charge, and R. L. PENDLETON, of the University OF California. MACY H. LAPHAAI, Inspector, Western Di\asiON. [Advance Sheets — Field Operations of tlie Bareau of Soils, 1914.] ■,logy-Geopnysics Library. :7 Geology r-ity of California " ^-, CA 90024 WASHINGTON: GOVERNMENT PRINTING OFFICE 1916. BUREAU OF SOILS. Milton "Whitney, Chief of Bureau, Albert G. Rice, Chief Cleric. SOIL SURVEY. Curtis F. Marrut, In Charge. G. W. Baumann, Executive* Assistant. COMMITTEE ON THE CORRELATION AND CLASSIFICATION OF SOILS. Curtis F. Marbut, Chairman. Hugh H. Bennett, Inspector, Southern Division. W. Edward Hearn, Inspector, Soutliern Division. Thomas D. Rice, Inspector, Northern Division. W. E. McLendon, Inspector, Northern Division. Macy H. Lapham, Inspector, Western Division, J. W. McKericheb, Secretary, Issued December 16, 1916. U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF SOILS— MILTON WHITNEY, Chief. IN COOPERATION WITH THE UNIVERSITY OF CALIFORNIA, AGRICULTURAL EXPERIMENT STATION, THOMAS F. HUNT, DIRECTOR; CHARLES F. SHAW, IN CHARGE SOIL SURVEY. SOIL SURVEY OF THE URIAH AREA, CALIFORNIA. BY E. B. WATSON, OF the U. S. Department of Agriculture, in Charge, and R. L. PENDLETON, of the University OF California. MACY H. LAPHAM, Inspector, Western Division. [Advance Sheets— Field Operations of tlie Bureau of Soils, 1914.] WASHINGTON: GOVERNMENT PRINTING OFFICE. 1916. LETTER OF TRANSMIHAL U. S. Department or Agriculture, j Bureau or Soils, i Washington^ D. 6'., Ap^il IJf, 1916. i Sir : In the extension of the soil survey in the State of California during the field season of 1914 a survey was made of the Ukiah area. This work was done in cooperation with the University of California Agricultural Experiment Station, and the selection of the area was made after conference with State officials, I have the honor to transmit herewith the manuscript report and map covering this area and to recommend their publication as ad- vance sheets of Field Operations of the Bureau of Soils for 1914, as provided by law. Respectfully, Miltgn Whitney, Chief of Bureau. Hon. D. F. Houston, Secretary of Agriculture. a CONTENTS. Page. Soil Survey of the Uriah Akea, California. By E. B. Watson, of the U. S. Department of Agriculture, in Charge, and R. L. Pendleton, of THE University op California 5 Description of the area 5 Climate 12 Agriculture 1 14 Soils 20 Residual soils 24 Mariposa series 24 Mariposa loam 25 Aiken series 26 Aiken stony loam 26 Aiken loam ■. 27 Olympic series 28 Olympic stony loam 29 Olympic loam 29 Climax series * 30 Climax clay adobe 30 Miscellaneous 31 Rough mountainous land 31 Soils derived from old valley-filling material 32 Corning series 32 Corning loam 32 Corning gravelly loam 33 Corning gravelly clay loam 34 Pleasanton series 35 Pleasanton gravelly loam 35 Pinole series 36 Pinole sandy loam 36 Pinole loam 37 Pinole gravelly loam 38 Soils derived from recent alluvial deposits 39 Yolo series 39 Yolo fine sandy loam, stream-bottom phase 40 Yolo loam 41 Yolo gravelly loam 42 Yolo silt loam. 44 Yolo silty clay loam 45 Tehama series 46 Tehama loam 47 Tehama gravelly loam 47 Tehama silt loam," poorly drained phase 47 Honcut series 48 Honcut loam, red phase 48 Honcut gravelly loam, red phase 49 Dublin series 49 Dublin clay 50 Miscellaneous material 51 Riverwash l 51 Summary 51 3 ILLUSTRATIONS. PLATES. Page. Plate I. View of Potter Valley, looking south 16 II. Fig. 1. — View over Coyote Valley, looking south. Fig. 2. — Rougli mountainous land, showing characteristic topography and forest cover 16 III. Fig. 1 — Hops on stream bottom soils of the Yolo series. Fig.2. — Dry-wine grapes on Pinole gravelly loam 32 IV. Fig. 1. — Section in material of Corning gravelly clay loam. Fig. 2. — . Peach orchard on Corning gravelly clay loam 32 V. Fig. 1. — Section in old valley-611ing material of Pinole gravelly loam. Fig. 2. — Stream-bottom soils of the Yolo series, near Ukiah 32 FIGURES. Fig. 1. Sketch map showing location of the Ukiah area, California .- 5 2, Sketch map showing location of arable valleys in the Ukiah area 6 MAP. Soil map, Ukiah sheet, California. 4 SOIL SURVEY OF THH UKIAH AREA, CALIFORNIA. By E. B. WATSON, of the U. S. Department of Agriculture, in Charge, and R. L. PENDLETON, of the University of California. DESCRIPTION OF THE AREA. The Ukiah area embraces the arable valleys of the Russian River drainage system in Mendocino County, Cal., together with a portion of the Coast Range Mountains adjacent thereto. It comprises an area of 303 square miles, or 193,920 acres, in the southeastern part of Mendocino County, and extends from the southern boundary of the county northward to the limits of the agricultural land in the Russian River drainage basin. The area is about 3(j miles long and from 7 to 12 miles wide. The base map used in plotting the soils was constructed by plane- table traverse by the field party, no pub- lished map suitable for the purpose being available. The Coast Ranges of northern Cali- fornia occupy a belt 50 to 70 miles wide, extending from the coast eastward to the Sacramento Valley. This region is com- posed of a series of roughly parallel ridges and valleys, or basins, wliich in the south- em part of Mendocino County have a trend nearly parallel to the coast. One of these large valley basins is drained by the upper part of the Russian River and constitutes the principal part of the survey. Within this basin are located several arable regions separated by rougher hilly areas. Each of the arable areas has a distinctive name. As an aid to a clear understanding of their location and relationship, the sketch map (fig. 2) is given. This shows the different arable valleys within the survey, including the large valley or basin, which was partly or completely filled at an early date and out of which the Redwood, Calpella, Coyotte, and Ukiah Valleys subsequently were formed. About 5 miles east of the northern part of this main trough or basin is a short and broad depression, Potter Valley, the drainage of which crosses the intervening rtdge and unites with the main Russian River drainage. This valley is included in the survey and is 5 Fig. 1. — Sketch map showing location of the Ukiah area, California. FIELD OPERATIONS OF THE BUREAU OF SOILS, 1914. Pio. 2. Sketch map showing location of arable valleys in the Ukiah area. SOIL SURVEY OF THE URIAH AEEA, CALIFORNIA. 7 indicated on the sketch map. These are the areas usually known as the upper Russian River valleys, and outside of these comparatively level areas and three small valleys in the southern part of the area, the drainage basin of the Russian River is untillable. The elevation of the floors of the several valleys varies from about 475 feet at the lower end of Sanel Valley in the southern part of the survey to 870 feet in the Laughlin Flat in Redwood Valley, and to about 1,000 feet in the upper part of Potter Valley. The gradient of the Russian River varies considerably in different parts of its course. Calculations made from the profile of the North- western Pacific Railroad indicate that the gradient through the gorge at the lower end of the area surveyed is about 15 feet per mile. Just above this, or from the lower end of Sanel Valley up to Calpella, at the junction of Forsythe Creek and the Russian River, the gradient varies from 7 to 10 feet per mile. The gradient of the East Fork of Russian River through Potter Valley is comparatively low, but that through the gorge leading from the valley probably is twice as great as in the valley. The arable valleys are mainly from 1 mile to 3 miles wide. They are not continuous, but are separated by intervening hills and ridges, which are traversed in places by narrow connecting stream gorges. From these nearly level valley floors the hills rise rather abruptly to elevations of 1,500 to 2,500 feet above them, or from 2,000 to 3,000 feet above sea level. Mount Sanhedrin, 6,200 feet high, about 10 miles northeast of Potter Valley, is the highest mountain in the re- gion. Duncan Peak, which is a conspicuous feature of the landscape near Hopland, is 2,700 feet high. The watersheds on both sides of the drainage basin are about 2,500 to 3,000 feet high, with passes through them about 1,000 feet lower than the summits. These hills for the most part are rounded, and the native vegetation varies from grass with scattered trees to a heavy covering of chaparral and a thick growth of trees on sheltered slopes. Springs abound in the hills. Some of these carry lime in solution and have made small deposits of travertine or of impure limestone; others contain iron and other minerals, and some are hot. Many of the springs are re- puted to be medicinal, and health resorts have developed about them. The drainage of the entire area is carried by the Russian River, which flows southward through the center of the area, with important tributaries from both the east and west. The drainage of the hills is very well established, and drainage channels of relatively high gradients reach into every part of the hilly areas. The drainage of the vallej^ floors is generally complete, but there are a few places where it is imperfect. The streams of the region are mainly perennial in the sections underlain by consolidated rocks, but in the alluvial valleys during the summer they sink into the gravels and disappear. 8 FIELD OPERATIONS OF THE BUEEATJ OF SOILS, 1914. The several arable valleys differ from each other in their physical characteristics. Avhich have influenced their settlement and develop- ment, SO that they can best be described separately. Potter Y alley. — Potter Valley lies in the extreme northeastern part of the TJkiah area and is drained by the East Fork of the Russian River. No very large streams enter it. The valley is about 7 miles long and 2 miles wide. It is characterized by a broad, level floor, which seems to be a recently drained basin, merging into low alluvial fans having a gentle slope up to the surrounding hills (PI. I). A part of the floor of the valley has until recently been poorly drained, and the effect of this condition is seen in the character of the soil. Remnants of old valley-filling material, rising from 5 to 20 feet above the floor of the valley, occur in a nvnnber of places in the southern half of the valley, and remnants of a -still older valley filling, from 100 to 400 feet high, border the valley on the west, but there are no such remnants on the east. In the southeastern extremity of the valley, however, where Mewhinney Creek enters, there are high remnants of old valley filling. The first settlers found the valley parklike, with an open cover, including scattered trees of valley oak and small groves of various trees covering perhaps one-third of the area. They could plow many fields without the trouble of clearing. Although the soils are productive, markets have been more or less inaccessible, and as a result stock raising became the chief form of agriculture. The stock ranged in the hills and in the stubble fields after harvest, the hay and grain produced being used to fatten the animals for market. This type of farming has continued to the present time. The cause of the thin covering of trees in Potter Valley, while Redwood Valley just across the ridge to the west was densely wooded, is a matter of interest. The most probable explanation is that there is less rainfall than in Redwood Valley. It is shown in the discus- sion of climate that there are variations in the rainfall in different parts of the area, and the fact that Redwood Valley is about 6 miles nearer the coast and has a pronounced gap in its western wall (Forsythe Creek Valley) through which the ocean winds may blow, while Potter Valley has a relatively high ridge to the west of it. probably accounts for the difference in precipitation. The more open cover was, no doubt, one of W\^ main reasons for this valley being settled much sooner and more completely than RedAvood Valley. The large proportion of recent alluvial soils and the dis- tance from markets have been important factors in determining" the type of agriculture followed. Redwood Valley. — Redwood Valley is the most northern of the valleys drained by the central fork of the Russian River. It is roughly triangular in shape, about 4 miles wide and 5 miles long, SOIL SURVEY OF THE URIAH AKEA, CALIFORNIA. 9 with its base lying to the south and the apex to the north, where the Russian River enters the valley. Forsythe Creek, which enters from the west, carries much more water than the central stream. Redwood Valley is characterized by a narrow river flood plain and a broad expanse of old alluvial valley filling or river terrace from 10 to 75 feet above the flood plain. It is bounded on the south and southeast by high hills of old unconsolidated valley-filling ma- terial from 400 to 600 feet high. There are no high areas of old valley-filling materials at the north end of tha valley. The greater part of Redwood Valley originally was heavily forested with a growth of oak, fir. and manzanita. Apparently there was some open country in the northern part. The dense growth of timber retarded settlement. The bottoms were found to be very productive and were cleared at an early date. The bench lands constituting most of the valley were not so well suited to grain pro- duction, the only type of farming attempted. The belief became fixed that the bench lands were poor, and the dense covering made the cost of clearing high. These factors have materially modified the development of this valley, as compared with that of Potter Valley and Ukiah Valley. These valleys were settled about the same time, but at present Potter Valley and Ukiah Valley are almost entirely cleared and farmed, while a large part of Redwood Valley is forested. Interest in the possibilities of growing fruit on the bench lands is now being manifested. There are no commercial orchards of bear- ing age in the valley, but home orchards indicate the suitability of the land for fruit production. Cold Creek Valley. — Cold Creek Valley is small and not very im- portant agi'iculturally. It is located a few miles south of Potter Valley. Cold Creek is a tributary of the East Fork of the Russian River. The part of Cold Creek Valley included in this area is about one-eighth mile wide and 4 miles long. The valley extends beyond the area surveyed. The valley of Cold Creek is interesting because it evidently belongs to a middle-aged stream which is a tributary to a very youthful stream. The East Fork of the Russian River flows with a high gra- dient through a V-shaped gorge. It has a youthful topography. Cold Creek, a tributary, flows at a much lower gradient, as is evidenced by the size of the stones in its bed. and has a distinct flood plain and also a terrace. It has attained middle age. Holway^ has established the fact that Cold Creek has lost a large tributary, Scott Creek, by a large landslide which diverted the waters to Clear Lake and thence to the Sacramento River. This probably has a bearing on the anomalous condition just noted. 1 Holway, " The Russian River," Univ. of Cal. Pub. in Geog., vol. 1, Ko. 1. . 42235°— 16 2 10 FIELD OPERATIONS OP THE BUREAU OF SOILS, 1914. Cdlpella Valley. — Calpella Valley lies between the two large rem- nants of old valley filling just south of Redwood Valley. This is a small valley, barely one-half mile wide, and 2 miles long. It com- prises a very narrow flood plain, and above this a series of terraces which blend into each other and are bounded on both the east and the west by the high eroded early valley filling. Although this valley was settled at an early date and was on the main thoroughfare for travel north and south, much of it is un- cleared and undeveloped. It has had about the same agricultural history as Redwood Valley. Coyote Valley. — This valley lies east of Calpella Valley across a high ridge of early alluvial-fan or old valley-filling material (PL II, fig. 1). It evidently is a recent valley carved out of the old valley- filling deposits by the East Fork of the Russian River, which flows through it. It is hardly 1 mide wide and is 2^ miles long. The soils occupy mainly a low terrace, modified in places by recent fan de- posits, and are quite productive. JJkiah Valley. — The Ukiah Valley is the most important of the arable valleys in the area. It lies south of Calpella and Coyote Val- leys, near the center of the area surveyed. It is from 2 to 4 miles wide and about 10 miles long. The Russian River flows through its entire length, and several fairly large streams enter from both sides. It is characterized by a wide flood plain of the Russian River, by low, fertile recent alluvial fans, formed by several of the smaller lateral streams, and by low bench lands bordeiing the present flood plains and having a topography well suited to cultivation. This valley is intermediate in physiographic features between Potter Valley and Redwood Valley. Its forest covering was also probably intermediate in density. Its productive soils, found in large bodies, and its location are fac- tors which have encouraged development. Along Robertson Creek, which enters the southern part of the valley from the west, there is a small extension, the characteristics of w^hich are much the same as ihose of the main valley. Knights Valley. — Knights Valley is south of Ukiah Valley, and is separated from it by a low ridge covered by residual soils. This is a small valley with its axis lying oblique to that of the main valleys. It is about 3 miles long in its greatest extension, very narrow at its upper end, and 1^ miles wide at its lower end. The drainage of this valley is carried by MciSTab Creek, which unites with the Russian River about a mile below the valley. The upper or western extension of the valle}^ has a good slope, but the lower part is basinlike. The topography in this part is level and the soils are heavy, indicating deposition from quiet waters. SOIL SURVEY OF THE URIAH AREA, CALIFORNIA. 11 Sanel Valley. — South of Knights Valley is the Sanel Valley, which is quite irregular in outline. It is about 5 miles long and 1 mile wide, with a small side valley at the northern end extending westward from Largo, a larger side valley at the southern end extending westward, and a large extension on the east side. This valley is characterized by a wide flood plain and relatively small alluvial fans and a relatively large deposit of old valley filling in the southern part. The soils are very productive, and the large area of smooth flood plains has encouraged its development. McDowell Valley. — McDowell Valley is a small valley lying east of Sanel Valley across a narrow ridge. This valley is about 2^ miles long and 1 mile wide. It is narrower at the north, widening out somewhat toward the south. McDowell Creek carries its drain- age westward through the narrow ridge into the Russian River. McDowell Valley differs from the other valleys in the area in having no flood plain along the stream which drains it, the valley floor lying well above the bed of the stream and about on a level with the lowest part of the inclosing rim. Apparently the depres- sion was filled to the rim, and later the stream cut down the outlet, but it has not yet succeeded in taking out any considerable amount of the original valley filling. The gorge has been eroded 60 to 75 feet below the valley floor. The valley apparently was largely for- ested originally, and considerable timber remains in places. A large part has been cleared. The soil is fairl}^ productive, comparing very favorably with the bench land of Ukiah and Redwood Valleys. There is one very small valley, not indicated on the sketch map, on a side stream which enters the gorge of the Russian River at Echo. The soils of this valley are derived from flood-plain and low alluvial-fan materials and are very productive. Before the advent of the white man the Ukiah area was inhabited by the Pomo Indians. These were peaceful, domestic Indians, who derived their living from hunting, fishing, and gathering acorns and wild fruits. Apparently very little of the land was cultivated. Be- tween 1850 and 1855 a few settlers located in Ukiah Valley and Potter Valley. From 1855 to 1860 settlement was quite rapid, and Mendocino County was organized in 1859, with Ukiah as the county seat. The centers of settlement were Sanel Valley, Ukiah Valley, and Potter Valley, which seem to have been settled and developed at the same time. Since about 1860 the development of the region has been gradual. About 75 per cent of the early settlers came from Southern and Central States, and the remainder from other parts of the United States and from foreign countries. The Indians have decreased in number until only a few^ small settlements remain, scattered through- out the area. The white population has continued predominantly 12 FIELD OPERATIONS OF THE BUEEAU OF SOILS, 1914. Anglo-Saxon. A few Italians and Swiss have settled in the region in the last 10 j^ears and are engaged mainly in grape growing. There are but few Chinese and Japanese, and they are mainly laborers. The rural population is principally confined to the level valleys. The population of the foothills is very sparse. The three political townships of Potter Valley, Ukiah, and Sanel were given a popu- lation of 6,587 in the last census. These townships are nearly identi- cal with the area surveyed. The area is traversed by the Northwestern Pacific Railroad, which follows approximately the course of the Russian River from the southern boundary of the area to Redwood Valley Station, in the northern part. Here it turns to the northwest, and crosses the divide to Willits and Eureka. To the south this railroad gives connections with San Francisco. A State highway is being built approximately parallel to the rail- road, and is nearing completion. This has a solid roadbed of easy grade, making travel easy at all times of the year. In addition, there is a good system of roads reaching all the agricultural areas, and means of communication are as good as the nature of the country will permit. Ukiah is the principal town in the area. It is situated on the rail- load in the Ukiah Valley. Its population is reported in the 1910 census as 2,136. Ukiah is the business center of the valley and the shipping point for the ranches back in the hills for many miles. A number of stages operate betM^een this point and various towns and pleasure resorts in the Coast Range. The small town of Potter Valley is the trading center of the valley of the same name. There is no railroad in this valley. Calpella is a small town in the Calpella Valley. Ilopland is located near the center of Sanel Valley on the railroad. It has grown up since the railroad was constructed. Old Hopland, 1 mile to the east across the river, was the business center of the valley during the days of the toll roacls. Hopland has a popu- lation of about 200 people, and Old Hopland about 100. Echo, Cum- miskey, Pieta, Fountain, Largo, Henry, El Roble, Redwood Valley, and Laughlin are shipping points on the railroad. All the grain and hay produced are sold within the area. The live stock, hops, and fruit are mainly shipped south to the bay region, but some is sold in the lumbering towns to the north. CLIMATE. The climate of the Ukiah area resembles that of the Great Interior Valley of California in that it has a rainy season of moderate tem- perature and a dry season with high temperatures, but it differs in that the rainfall is greater and the temperature range is less. It is SOIL SURVEY OP THE UKIAH AREA, CALIFORNIA. 13 intermediate in climate as well as in position between the Interior Valley and the coast region of Mendocino County, which has a still greater rainfall and cooler simimers. Its climate is very similar to that of the neighboring valleys in the Coast Eange. The rainy season occurs in the winter months, from the first of November to the last of April. The five months from May to September, inclusive, constitute the summer or dry season. The mean annual precipitation at Ukiah, the only place in the area at which official Weather Bureau records are kept, is 37.3 inches. Of this amount 2,2 inches falls in the five months of the dry season. The mean annual temperature is 57.6° F., which is practically the same as that at Santa Rosa, 55 miles to the south. It averaj^es dur- ing the rainy season about 49°, or nearly 3° colder than at Santa Rosa. From May to October, inclusive, it averages about 66", or nearly 2° warmer than at Santa Rosa. This apparently is due to the fact that this valley is not so open toward the sea as Santa Rosa Valley. The average date of the first killing frost in the fall is Novem- ber 1, and of the last in the spring April 14. The earliest recorded date of killing frost in the fall is October 16, and the latest date in the spring May 2. There is a normal growing season of 201 days. There are very few days when the temperature goes above 100°, and the hot spells are of short duration. Snow very seldom falls, and lasts but a few hours. The great variation in the width of the valley, its elevation, and relation to gaps in the hills through which the winds come, makes variations in precipitation, temperature, and winds in different parts of the area seem very probable, but actual data on this subject are scarce. A record of the rainfall at the power plant at the head of Potter Valley for three seasons, compared with the rainfall at Ukiah for the corresponding seasons, shows 10.7 inches less rainfall in Potter Valley. It seems probable that certain parts of the area have a greater rainfall than Ukiah, so that the extreme variations between different parts of the area is probably much greater than 10 inches. The variations in temperature, frosts, and winds also prob- ably is considerable. This matter of local variation in climate must be taken into consideration in fruit growing in different parts of the area, but definite information on this point can not be given owing to the lack of data. On the whole the climate is well suited to the production of gen- eral farm crops, alfalfa, hops, grapes, and most tree and bush fruits. It is not well suited to citrus fruits ; there are some areas in the hills, from 500 to 1,000 feet above the valley floors, where oranges can be grown, but the area of suitable soil in these localities is very small. 14 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1914. Relatively few fogs occur, and these generally disappear early in the day. High winds are very rare. The coast breeze during the summer season reaches the valleys through several gaps, notably in Redwood Valley through Forsythe Creek gap. The accompanying table, giving the normal monthly, seasonal, and annual temperature and precipitation, is compiled from the rec- ords of the Weather Bureau station at Ukiah : Noniial mouthly, seasonal, and annual temperature and precipitation at XJkiah. Temperature. Precipitation. Month. Mean. Absolute maximum. Absolute minimum. Mean. Total amount for the driest year. Total amount for the wettes; year. 'F. 44.7 45.1 47.7 °F. 86 77 82 'F. 20 12 18 Inches. 6.65 8.35 6.17 Jnchea. 2.41 1.23 7. OS Inches. 5.81 30.75 12.53 Winter 45.8 86 12 21.17 10.72 49.09 March 50.2 55.0 60.4 85 92 102 24 27 30 5.55 2.45 1.26 0.68 0.80 1.63 4.56 0.00 May.. . 0.00 Spring 55.2 102 24 9.26 1 3.11 4.56 June 67.7 73.4 71.8 107 112 114 36 39 40 0.34 0.02 0.01 0.65 0.00 Trace. 0.10 Julv 0.04 August. 0.00 71.0 114 36 0.37 0.65 0.14 September 65.7 58.4 51.2 108 98 80 32 26 22 0.57 1.78 4.15 0.82 1.24 2.02 0.48 October 2.36 November 5.14 Fall 58.4 108 22 6.50 4.08 7.98 Year 57.6 114 12 37.30 18.56 61.77 AGRICULTURE. Cultivation of the soil began with the first settlement of the area, between 1850 and 1860, and it is probable that the better alluvial soils were cleared during or soon after this period. Stock raising was the principal industry from the first, and the hay and most of the grain produced on the cultivated area was used for feed for the stock. It was so far to market that little besides stock could be taken out. Family orchards w^ere set out and as a rule did very well. Wheat was milled for home consumption. In 1889 the North- western Pacific Railroad was completed to Ukiah, and this gave access to markets, but the farmers have been very slow to change their established system of agriculture, especially in the northern SOIL SURVEY OF THE UKIAH AREA, CALIFORNIA. 15 part of the area. Soon after the advent of the railroad a few com- mercial orchards of pears and prunes were set out. These have been profitable. There is very much less fruit grown in this area than in the part of the Russian River Valley to the south within the adjoining county of Sonoma. This is due not to differences in soil or climate, but to the later development of transportation facilities and to the conservative character of the people. Fruit growing seems destined to be an important industry in the area, notwithstand- ing the fact that its extension northward has been slow. The growing of hops began in the seventies and was a well-estab- lished industry by 1877. The soils of the alluvial stream bottoms were found particularly adapted to hops, but the industry developed irregularly, owing to the fluctuations in the market value of the crop. At present it is one of the largest industries of the area. Tobacco was grown in a small way about 1861, and it is claimed that the crop did well. At the present time, however, it is not grown. Grapes for making wine and for table use have been grown in the area probably since the earliest settlements. Some vineyards contain large vines 30 to 40 years old. The early development of this in- dustry was slow, but about 1900 grape growing received an impetus and has expanded steadily since that time. It is claimed that the phylloxera prevalent in the districts south of the survey has not yet passed the barrier of uncultivated hill land to the south, and that the vineyards of this area are free from that disease. The vineyards, where given proper care, have done well. They have been put out mainly on the bench and rolling lands, as the bottom lands were used for hops, alfalfa, and grain. They were introduced not to replace other crops, but to supplement them by being planted on soils not so well suited to these other crops. It is impossible to give statistics in regard to live stock or crops in the area for the reason that the area is only a part of the county and all figures available are for the county as a whole. The in- formation given in the following pages in regard to agriculture in the area at the present time is mainly the result of observations in the field, supplemented wherever possible by published statistics. The principal kinds of live stock, named in order of their im- portance, are cattle, sheep, hogs, and horses. The rolling hills indi- cated on the accompanying soil map as Rough mountainous land are used for ranges for cattle and sheejo (see PI. II, fig. 2), Feed grown on the arable land, including hay, grain-hay, and alfalfa, is used by some ranchers to carry the stock through the periods of scanty pasturage and to fatten them; others depend on the range entirely. Most of the foothill soils seem best suited to pasture. The proportion of arable land devoted to the production of winter feed for stock is growing steadily less, as it is found much more profitable to grow 16 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1914. hops, grapes, and fruit than it is to grow feed, except in the case of alfalfa. Few horses are raised, except for farm use. Hogs are raised in considerable numbers. They are raised on the range, but are fed grain in addition. There is a large poultry farm in Hopland; the remainder of the poultr}^ in the area is in small farm flocks. Considerable grain is grown, especially in the northern part of the area and in Potter Valley. Wheat is the principal grain crop, closely followed by oats, with barley and corn having a smaller acreage. However, not enough grain is grown for home consump- tion, and flour and feed are shipped in. A larger acreage of grain- hay is grown, and all of this is used for stock feed. The grain, especially corn, does best on the alluvial soils consisting of the river flood plains and recent alluvial-fan soils. This is due not only to their high productiveness, but also to the fact that the supply of moisture can be conserved by proper cultivation during the dry sea- son better than on the bench soils. Grain is grown, on the Pleasanton and Pinole soils, but the yields are often very light and on the average the practice is not found profitable. Alfalfa is a new crop in the area, but is gaining in favor very rapidly. It does well on soils of the Yolo series, where it can be grown profitably without irrigation. In Potter Valley the crop is grown on the Yolo soils occurring upon the alluvial fans. The up- land soils, however, such as those of the Pinole series, are not so well suited to alfalfa, though if abundant water could be supplied for irrigation it seems probable that the crop would do fairly well on the bench soils. Irrigation is being tried on the alluvial soils. It seems profitable and probably will be extended, the yields being increased by this means. The Eussian River Valley is one of the main hop-growing centers of California, Mendocino and Sonoma Counties together reporting more than one-half the hops produced in the State. This is an intensive crop, requiring a large expenditure per acre in the way of equipment and labor, but giving under favorable conditions very large returns. Hops are grown from root cuttings. These are planted in hills about eight feet apart each way. After the vines begin to run they are supplied with supports. Two systems are followed in this area. In one system a permanent network of heavy wires is stretched over the field, about 16 feet above the ground. Strings reach from tlie wires to the ground and 6 vines from each hill are trained up these strings. This system costs about $50 an acre to install. The other system is cheaper, but it is claimed that not as good a quality of hops is raised. Poles about 7 feet long are set in each hill, and strings are stretched along the tops from pole to pole, forming a network over which the vines spread in their growth (PI. Ill, fig. 1). The owner usually cultivates the fields, but the work of cultivation in the hill, pruning, suckering, trimming, Report of Bureau of Soils, U. S. Dept. of Agriculture, 1914. PLATE I. Report of Bureau of Soils, U. S. Dept. of Agriculture, 1914. Plate II. Fig. 1.— View Over Coyote Valley, Looking South, Ridge of old vrtlley-filling niiiterial defining the valley on the right. Cleared areas on this ridge in distance planted to vineyards. Fig. 2.— Rough Mountainous Land, Showing Characteristic Topography and Forest Cover. SOIL SURVEY OF THE URIAH AREA, CALIFORNIA. 17 stringing, and training is given out by contract. This costs about $19 an acre if the overhead trellis is used, and $25 an acre where the small poles are used. T^Is work is done mainly by Indian or Japanese labor. Picking is paid for by the hundred pounds. After picking the hops are taken to large drying kilns, foimd on every hop ranch of any size, where they are sulphured and dried by arti- ficial heat, cooled, baled, and stored. It is reported that it costs ijbout 9 cents a pound to grow hops. The business is highly specu- lative because of the great fluctuation in price. Hops give a light crop the first year, come into full bearing the second year, and remain productive for many years. Hops in this area are grown almost exclusively on the stream-bottom phases of the Yolo silt loam and the Yolo fine sandy loam. In Potter Valley a few hopyards are found also on the alluvial-fan soils of the Yolo series. The pear industry is not extensively developed in the area, but there are a number of commercial orchards of fair size and new ones are being set out. The Bartlett is the only variety grown. Pears from this area bring top prices, as the quality is excellent. The orchards are well cared for and no blight was seen at the tima of the survey, although it has been troublesome in the past. The fresh fruit is shipped to eastern markets or sold locally to the can- neries. The inferior fruit is dried. What is said to be one of the most profitable pear orchards in California is located on the Yolo fine sandy loam, stream-bottom phase, near Old Hopland. Other orchards are found on the stream-bottom phases of the Yolo silt loam and the silty clay loam. Orchards are being set out on the Yolo soils of the alluvial fans and on the soils of the Pinole series. It seems probable that the Yolo silt loam and the Yolo silty clay loam of the alluvial fans will be found good soils for this crop. Its success on the bench soils is not so certain. Prunes are grown commercially in the area and rank with pears in importance. The French Petite prune is grown almost exclusively. The orchards are found mainly on the Yolo alluvial-fan soils, with some on the stream-bottom phase of the Yolo silt loam, and new orchards are being set out on practically all the soils in the area. The bearing orchards have been profitable, but the trees do not seem to have quite the vigor and growth of trees in other prune sections of the State. There are no bearing commercial orchards of peaches and apples in the area, but there are a large number of home orchards that in the main have done well. A few commercial orchards are being set out on tlie Pinole and other bench soils, and it seems probable that these soils are well suited to the production of both fruits. Grapes are more important than any other fruit in the area. They are grown almost exclusively for wine. The vineyards are found 42235°— 16 3 18 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1914. mainly on the higher, drier, and lighter textured soils and are located largely on soils not so well suited to other crops. The Pleasanton i>,nd Pinole soils are particularly suited to grapes (PI. Ill, lig. -2), but they do well on practically all the soils of the area. The richer alluvial soils, however, may give greater returns in other fruits. The residual Mariposa loam does not seem so well suited to the grape. It is reported that the grapes grown on the upland soils of the val- leys, those of the Pleasanton and Pinole series, are of better quality and have a higher content of sugar than the grapes grown on the 11 '.ore recent alluvial soils and bring a better price at the wineries. A start has been made toward putting the eroded phases of the Pinole loam and gravelly loam into grapes, and the prospects are very encouraging so far as the growth of the vines is concerned. There is some apprehension with respect to markets. For a number of years prices have been satisfactory and profits correspondinglj'^ high, but growers fear that adverse legislation may cripple or destroy the market for wine. Table grapes are grown in a small way, and it is claimed that many varieties do very well. These grapes are sold at local markets, but it is evident that these markets could be very easily oversupplied. No raisin grapes are grown, as the climate is not suitable for curing the product. Casaba melons are grown for seed in the Potter Valley on the heavier members of the Yolo series of soils. The melons do very well on these soils, and the industry has assumed considerable local importance. In the northern part of the area, especially in Redwood Valley, considerable land remains to be cleared. The clearing as a rule is done at odd times by the owners and it is difficult to give the cost per acre. There are few very large stumps to be taken out, the oak stumps being the most difficult to remove. The cost probably is between $25 and $50 an acre, depending on the nature of the forest growth. The usual custom is to continue the clearing over a number of years, which allows many of the stumps to rot out. No data concerning the size of farms or the density of rural popu- lation are available. The impression gained from observations in the field, however, is that the population in the valleys proper is not so dense as in other more highly developed valleys to the south. The population in the hill country on the borders of the area is very sparse. The farms have never been large compared with the bonanza farms of the San Joaquin and Sacramento Valleys, and extensive types of agriculture have never developed. The farms are of medium size. In a few cases they are being subdivided. The annual rainfall of this area, averaging between 35 and 40 inches, is considered sufficient for all agricultural purposes. This SOIL SURVEY OF THE UKIAH AREA, CALIFORNIA. 19 rainfall occurs in the winter, but by careful cultivation moisture can be conserved and made to last throuMiout the summer. The farmers have not been forced to ii-rigate, as the rainfall is sufficient to give at least fair returns Avith ordinary farm crops. But as the types of farming have become more intensive of late years the need of irri- gation has been felt. No general irrigation system has been at- tempted, but a number of farmers have established individual sys- tems. There has been a small amount of gravity irrigation from springs on some of the hill farms, but the water so far utilized has been obtained mainly by pumping from the Russian River or from the underlying gravels. The Russian River in the summer often has no surface flow, but there is always a strong flow through the gravels below the bed. This has been utilized by a few farmers along the banks of the river. The water is pumped by electric or gasoline power to a height of 15 to 25 feet, and is distributed over the field by gravity. Such irrigation so far has been used only for alfalfa and garden crops. Many of the side streams that enter the valley are fed by springs and have a perennial flow through their courses in the hills. But as soon as t\\ej reach the valley floor the waters sink into the gravel and there is no surface flow except during the rainy season. Unquestionably permanent sources of water supply could be obtained near these streams if the gravel beds could be reached, but the extent of the gravel is not certain. Some wells on the uplands, away from the streams, might prove permanent. Others would certainly be only temporary. The chances of getting a cer- tain water supply seem better as the center of the valley or the beds of the side streams are approached. The drainage of McDowell Valley passes out through a gorge cut in bedrock. This stream goes dry in the summer, and unless there is some subterranean outlet to the drainage of the valley, Avhich seems improbable, this indicates that there is no excess supply of water in the gravels underlying McDowell Valley and no large water supply for irrigation purposes. Potter Valley seems to have a large supply of subterranean water, which might be pumped for irrigation. There is always a stream of water flowing out of the valley through the rock-bottomed gorge of the East Fork. The amount of outflow has increased since the headwaters of the Eel River have been diverted and brought to Potter Valley for power development. It has been proposed to use the water from this power plant for irrigation, as it could be taken by gravity to all parts of the valley, but so far only a very little is used. The farmers state that the supply is intermittent and that water is likely to be lacking when most needed. The company man- aging this plant has undeveloped reservoir sites which, when devel- 20 FIELD OPZRATIOXS OF THE BUREAU OF SOILS, 1914. oped, will, it is cliiin«?d, enable them to run constantly, and in this case the water from their plant will be a valuable asset to t^ie valley for irrigation. The value of land in the area has increased greatly w^ithin the last few years. The best alluvial lands are selling at prices ranging from $200 an acre for unimproved land to $r)00 an acre for land in bearing vineyards, orchards or hop yards. The bench lands sell for $75 to $200 an acre, according to improvements. The hill lands suitable only for pasture are valued at $5 to $20 an acre. Some of the hill land, covered only with chaparral, is practically worthless. Very little hardpan is encountered in the area, and it has no in- fluence on the land values. Some hardpan outcrops on the hillsides of the very oldest valley filling. Where observed this is about a foot thick, of medium hardness, brown in color, and contains waterworn cobbles, A large part of the labor on the small ranches is performed by the owners. The Indians in the area are employed as laborers in the hop fields. They are also employed to clear land and cut wood in the winter and in a small way to do general farm work. Numbers of Japanese are employed in the hop fields and in the vineyards and orchards. There is a fair supply of white labor at all times, and during the busy season of hop, fruit, and grape picking this is aug- mented by an abundance of transient labor. Wages are comparable with those paid in adjoining parts of the State. SOILS. The valleys in the Ukiah area have had a complicated geomorphic history that has not yet been entirely worked out. Holway has studied some of the problems, and the following discussion is based on his work,^ supplemented by observations of the field party. It seems certain that all the territory lying west of the eastern boundary of Mendocino County and embracing the area surveyed was at one time reduced to a peneplain surface and drained directly west- ward into the Pacific Ocean. In the latter part of the peneplain period, probably near the beginning of Quaternary time, there were local foldings and an uplift of the region as a whole. The main foldings have been accompanied and followed at different times by minor foldings or faults. A great many of these have occurred. A long, straight valley was formed parallel to the general direction of the Coast Eange in this locality. Apparently the northern part of this valley was the result of a syncline and the low^er part, in what is now the gorge of the Russian River in the southern part of the 1 Holway, " The Russian River, a Characteristic Stream of the California Coast Ranges,' Univ. Cal. Pub. in Geog., vol. 1, No. 1. SOIL SURVEY OF THE UKIAH AEEA, CALIFORNIA. 21 area, may be considered a '"fault-line valley," that is, a valley pro- duced by erosion but following the line of a fault because along such line erosion was easiest. The Russian River in its headward erosion from the south has been guided by these faults and foldings and has entered and drained this large valley. Therefore the depression, in- cluding the main agricultural valleys, is considered a structural valley, and the gorge in the southern part of the area an erosional valley. The main structural valley just mentioned, produced by the syn- cline which includes the arable valleys of Redwood, Calpella, Coyote, and Ukiah, was a large, elliptical depression extending from the head of Redwood Valley to the southern end of Ukiah Valley, a distance of about 18 miles, and averaging through most of its length from 3| to 4^ miles wide. This originally large valley has been modified by later developments in the rising and sinking of small parts and by being filled partly or entirely by deposits of alluvial fans or deltas from the side streams, notably Forsj^the Creek, and the east fork of Russian River. Immense quantities of material Avere deposited in the valley. The actual depth of this old valley filling is not known. One well in the southeastern part of Potter Valley was bored 400 feet through blue clays which are probably old valley-filling material. It probably is 1,000 feet thick in places. It has been eroded consider- ably since the first deposition and either carried away or reworked, but large remnants of the first filling still remain. These remnants are high and are badly eroded, and for the most part are nonarable, thus decreasing the size of the arable part of the valley and dividing it up into smaller valleys. From an agricultural standpoint this oldest eroded valley filling differs little from the adjoining mountain slopes. The later reworked portions of this old valley filling takes the form of river terraces and is arable. South of this main valley, which extends to the vicinity of Henry station, are smaller ones, partly structural and partly erosional in origin and having a more com- plicated geomorphic history than the large valley just described. Potter Valley evidently lies in another syncline which has had several lesser tiltings and which has been drained by the cutting down of the gorge across the ridge to the southwest. The large main valley received all the streams to the east and also the headwaters of the streams to the west for a short distance. This explains the peculiar direction of flow of such streams as Morrison and McDowell Creeks. They evidently have not been developed as tributaries of the present Russian River, else they would have a southwest trend. As it is, they have a northwest trend and are in line with streams on the west side of the Mendocino Ridge that flow into the ocean. They apparently are captured headwaters of these streams. 22 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1914. It seems probable that early in their historj'^ these valleys were lakes, for in the substratum of the old soils there are beds of silts and clays that must have been laid down in very quiet water. At the present time all the valleys are drained. This apparently has resulted from the combined action of the cutting down of the gorge at the south end of the vallej's giving an outlet to the waters, from the filling of the valleys above referred to, and probably from some crustal movements. The rocks forming the hills surrounding the Ukiah area apparently belong largely to the Franciscan series, which are described as prob- ably of Jurassic age ^ and consist of sandstones, shales, and conglom- erates which have undergone metamorphism. Some of these rocks have been little changed and others have been greatly changed. Some are very soft and weather and erode rapidly, while others are , harder and weather much slower, giving a more rugged outline to the hills formed by them. Among the harder rocks are the radio- larian cherts. Included with these sedimentary rocks are a number of igneous intrusives, some of which also have suffered great meta- morphism. The igneous rocks are, first, basalt or diabase, and, ?econd, periodites which have in general become thoroughly serpen- tinized. The beds and strata of these various rocks have been very much tilted, broken, and warped. In practically no case are the sedimentary rocks horizontal, as they undoubtedly were when they were laid down, but they are found now at all angles and usually are more nearly vertical than horizontal in position. Furthermore, there is very little continuity in the rocks. The fracturing and tilt- ing has taken place in great detail. As a result of this the residual soils derived from these rocks have very frequent changes and are extremely difficult to map. These hills evidently have occupied their present relative position for a long time, for they are deeply weathered; erosion has developed a drainage system that has reached ever}^ part of the area, and the hills are mainly rounded in outline rather than rugged. No limestone rock was observed in the area, and probably little is present. A few of the springs, however, carry a high percentage of lime probably extracted from the minerals of the rocks through which their waters circulate. According to analy- ses (made by the experiment station of the University of California) of samples collected during the progress of this survey, the soils of the area carry a fair percentage of lime, from 0.50 per cent to 1.50 per cent, but this apparently is largely in the silicate forms, with only small amounts in the carbonate forms. A few of the soils show field indications of being mildly acid, others apparently are neutral, and the soil of the Dublin series gives indications of having a high lime content. 1 San Francisco Folio, U. S. Geol. Survey, 1914, by A. C. Lawson. SOIL SURVEY OF THE UKIAH AEEA, CALIFOITNIA. 23 The soils of the Ukiah area fall into three general groups: (1) residual soils; (2) soils derived from old valley-filling material; and (3) soils derived from recent alluvial deposits. The residual soils result from the disintegration or weathering of the rocks in place. In the aggregate these form a very small proportion of the valleys proper, but they occur extensively in the hills surrounding the val- leys. Only small areas of the residual soils are arable. These arable portions occupy low hills and foot slopes at the edges of valleys, very small valleys back in the hills, and gentle slopes well up toward the top of the hills. Perhaps 2 per cent of the hill country is arable. The arable residual soils are classed with the Aiken series, including red soils ; the Mariposa series, with grayish-yellow soils ; the Olympic series, with brown soils; and the Climax series, comprising black soils. The rougher, nonarable portions of the residual soils, in Avhich differentiation of soil series and types is not warranted, are mapped as Rough mountainous land, which includes the greater part of the hills and mountains. The second group of soils results from the weathering of old valley- filling material. This material has been brought into the valley dur- ing former periods by streams and deposited as alluvial fans, deltas, and lake deposits. The deposits have been reworked in part a num- ber of times by streams and have been subjected to weathering in place, usually with the development of rather heavy and compact subsoils. These deposits are not now being added to by the agencies that originally made them, but, on the other hand, are being degraded by erosion. The material forming these soils is derived from all classes of rocks found in the hills. The soils derived from the old valley deposits are classed with the Corning series, comprising the red soils, the Pleasanton series, which has dark grayish brown soils, and the Pinole series, with light brownish yellow or grayish-yellow soils. The third general division includes the soils formed from recent alluvial deposits. They differ from the old valley-filling deposits in that they are yet in process of formation, have not been " aged " or weathered in place, and normally have rather porous, friable subsoils. They are derived from all classes of rock material eroded from the foothills and from the older valley-filling deposits. The soils in this division are classed with the Honcut series, including red to reddish- brown soils; the Yolo series, Avith brown soils; the Tehama series, with brownish-yellow or grayish-yellow soils; and the Dublin series, which has black soils. The Yolo series have stream-bottom phases, which are river flood plain soils. They differ from the alluvial-fan soils in being the flood plains of perennial streams, while the fans are the deposits of intermittent streams. This third di^ ision includes 24 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1914. Riverwash, a type of miscellaneous material of nonagricultural character. The following table gives the name and actual and relative extent of each soil tj'pe mapped in the area : Areas of different soils. Poi!s. Acres. Per cent. Soils. Acres. Per cenl^ Rough mountainous land 131,648 10,816 11,200 2,816 5,056 4,352 1,664 5,760 2,816 128 2,752 2,368 128 2,176 1,920 67.7 } 11.4 4.0 1 3.. 3.0 1 - 1.4 1 ..3 1.1 1.0 1,920 1,344 960 320 896 896 768 128 256 128 320 192 192 1.0 Tehama loam .7 Pinole loam .7 Erodfed jihase St ream -bottom phase .5 Corning loam .5 Stream-bottom phase .5 Heavy phase Yolo silty day loam .2 .2 Stream-bottom phase Yolo fine sandy loam, stream- Stream-bottom phase Honcut loam, red phase Tehama silt loam, poorly drained phase .1 Corning gravelly loam .1 Total Pieasanton gravelly loam 193, 920 Olympic loam RESIDUAL SOILS. Mariposa Series. The Mariposa soil is pale yellovv^ or yellow to grayish yellow^ or yellowish brown in color. The subsoil, where present, is- heavier than the surface soil and as recognized in this survey is grayish yellow or pale yellow to bluish gray in color. The bluish-gray color prevails wherever the subsoil extends much below the 6-foot section. The subsoil is underlain by bedrock, and this usually oc- curs within 6 feet of the surface. The topography is rolling or hilly to mountainous, and drainage is excessive, but the hills are round and smooth, broken only by occasional steep-sided ravines or marred in places by the marks of small landslides. Rock outcrops occur in places. The Mariposa series is residual in origin. The principal basis of differentiation from other residual soils in the area is its color. It is formed mainly by the weathering of the softer, unmetamorphosed or slightly altered sandstones and shales wiiich are probably cor- related with the geological formation known as the Franciscan series of rocks and which are intimately interbedded, upturned, broken, and generally mixed. Only one member of this series, the Mariposa loam, occurs in the area. As mapped it may include minor undif- ferentiated bodies of soils of the Altamont series, which includes brown soils of similar origin but is not recognized in this area, or of soils derived from old valley-filling deposits. SOIL SURVEY OF THE UKIAH AREA, CALIFORNIA. 25 MARIPOSA LOAM. The soil of the Mariposa loam consists typical!}^ of a pale-yellow or grayish-yellow loam from 1 to '6 feet deep, though in this survey the type includes yellowish-brown variations. The material is com- pact in structure, low in organic-matter content, and difficult to cultivate. The subsoil, where present, is a claj^ loam or clay. It is compact and impervious and is pale yellow or brownish yellow, with bluish-gray variations. The bluish-gray material is found at lower depths, next to the parent bedrock. The type is underlain by the shales and sandstones from which it is derived, and these may occur directly under the surface soil at a depth of 1 or 2 feet, or lie 10 to 20 feet below under the heavier subsoil. There are therefore two variations of this type, one with a shallow soil and the other with a deep subsoil. In the shallow areas there is little or no subsoil, and the surface soil rests directly on the bedrock at a depth of 2 or 3 feet, with an occasional outcropping of the bedrock. In the deeper areas the heavy subsoil is always present, and bedrock may not occur within the 6-foot section. These variations grade into each other, and they are not separated on the map on account of the practical difficultv of examining the soil section. The Mariposa loam is distributed throughout the area, occui-ring on the border of the valleys and occupying the lower foothills or ridges. It is bounded on the side away from the valleys by Rough mountainous land, which rises to higher elevations. In many places the boundary between this type and the Rough mountainous land is rather arbitraiy. The topography is rolling, but the hills are rounded and smooth. They rise from 100 to 200 and even 400 feet above the general level of the adjoining valley floor. These hills are parklike in appearance, being covered with native grasses, with a sparse growth of blue oak, valley oak, and buckeye. Manzanita grows on the broken slopes, and Douglas fir is found in places. In Potter Valley yellow pine and digger pine are found on the soils of this series, as well as on adjoining soils to a small extent. In many places the surface is marked b}'^ peculiar irregularities caused by landslides. These may cover an area from a few square rods to an acre in size. They occur where the soil is deeper and apparently are caused by a lessening of the cohesion through the saturation of the soil, which allows the soil to slide on the compact underlying clay. Erosion is active, but the surface, except for occasional ravines, is not broken or rough. Drainage is good to excessive. The type is used for pasture, and on account of the thin forest growth and the good growth of grasses it is highly prized for this purpose. Very little of it has been cultivated, and it seemingly has 42235°— 16 4 26 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1914. little value for crop production. Grain is very poor, and vineyards make a slow growth and are unproductive. Below are given the results of mechanical analyses of samples of the soil and subsoil of the Mariposa loam : Mechanical analyses of Mariposa loam. Number. Description. Fine gravel. Coarse sand. Medium sand. Fine sand. Very f^n? sand. £ilt. Clay. 573022 Soil Per cent. 1.0 1.1 Percent. 3.0 3.0 Per cent. 2.4 1.9 Per cent. 15.6 11.9 Percent. 23.6 17.3 Per cent. 34.7 34.4 Percent. 19.6 573023 Subsoil 30.6 Aiken Sebies. The soils of the Aiken series are red.^ The subsoil where present has the same color, or is somewhat lighter. The rock from which the soil is derived is usually between 2 and 4 feet below the surface, but in a few places it may lie below the 6-foot section. Rock outcrops are numerous. The topography is sloping to hilly, and surface drainage usually is excessive. The slopes in many places are quite steep. The soils of the Aiken series are residual in origin and are typically derived from igneous and metamorphosed igneous rocks of basic or quartz-free character. As occurring in this survey they are derived, apparently, from the Franciscan series of rocks, for the most part hard and highly metamorpho.sed, partly sedimentary and partly igneous in origin. These soils are differentiated from the Mariposa and Climax series on the basis of color, but it is found also that the Aiken soils are derived prevailingly from the metamorphosed and igneous rocks rather than from the sedimentary or feebly metamorphosed sedi- mentary rocks giving rise to the Mariposa and Climax soils. As mapped, however, the soils of the Aiken series probably include locally some small undifferentiated areas of soils which are derived from the sedimentary rocks and which if more extensive would be recognized under distinct series heads. The native vegetation of the series in this area consists of oak, fir, redwood, madrona, man- zanita, chamisal, poison oak, and a varied chaparral. The dense covering of trees and bushes is in sharp contrast to the growth on the Mariposa soil, which is open and parklike. AIKEN STONY LOAM. The Aiken stony loam is indicated on the soil map by stone symbols in color of the Aiken loam. The soil is a red or brownish-red to 1 Yellowish-red or orange Tariations occur in the present area. SOIL SURVEY OF THE UKLA.H AREA, CALIFORNIA. 27 rusty-red loam, containing a high percentage of angular fragments of rock. As a rule these fragments gradually increase in quantity with depth, bedrock being encountered at 2 to 4 or, in extreme cases, 6 feet below the surface. The soil is friable, but is rather difficult to cultivate, owing to its stony nature and the prevailing steeply sloping surface. Only two small areas of this tjrpe are shown on the map. Both occur in the southern part of the area, one near Cummiskey and the other on the Mendocino-Sonoma County line. Other bodies too small to map occur within the Rough mountainous land areas. The to- pography is steep to hilly, erosion is quite active, and drainage is excessive. The cleared areas of this soil are devoted to vineyards and young orchards, to which the soil is well suited. AIKEN LOAM. The soil of the Aiken loam is typically a light-red to brownish-red or yellowish-red loam usually from 1 to 2 feet deep, but in places having a depth of 4 feet. The yellowish or orange tint is often pronounced, and is much more strongly developed than in this type as mapped elsewhere. The soil is of friable structure and is easy to cultivate. It contains varying quantities of angular rock fragments, but not enough seriously to interfere with cultivation. The subsoil where present extends from the surface soil to the bedrock, and usually is light red or even yellow in color. The bedrock is encountered in most- places at depths of less than 4 feet, and rock masses in some places outcrop. This is an unimportant type. It occurs in small areas at the base of the hills, bordering the floors of the valleys, and also in compara- tively level areas back in the hills, where besides the areas shown there are many small areas too small to map. This type often in- cludes some undifferentiated alluvial or colluvial foot-slope material on the lower edge, and on the upper margin merges with the liougli mountainous land lying above it. It is sloping to steep in topog- raphy, and occupies some of the more nearly level parts of the hi1' region. It is all arable, but some of it is so steep that it can be tilled only with difficulty. Erosion is active and drainage good. Cleared areas of this soil are used for the production of fruit and garden crops. It is productive, but its value is limited by the fact that it occurs in small areas, is often inaccessible, and lies on steep slopes. As the development of the region progresses, however, more of the small areas of this soil occurring in the hills probably Av'ill be brought under cultivation. Aiken loam, heavy pJiase. — The soil of the Aiken loam, heavy phase, varies considerably in texture and color. Prevailingly it is a red or dark-red heavy loam or clay loam containing some small 28 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1914. angular fragments of the parent rock but not enough seriously to aifect cultivation. In this survey much of it is somewhat deeper red than in previous survey's. The subsoil is similar to the surface soil in color and texture, but contains more rock fragments. Bedrock is found at varj'ing depths, but lies usually between 3 and 5 feet below the surface. Only one area of this phase is mapped, a narrow strip on the eastern edge of the main valley near Largo, but many other bodies too small to map separately lie within the areas of Rough mountain- ous land. The surface is sloping to rather steep, erosion is active; and drain- age is fairly good. Some undifferentiated bodies of other types, notably the Climax clay adobe, too small to be shown on the map, are included with this heavy phase of the Aiken loam. The phase is used mainly in growing grain, of which the yields are good. Some orchards have been set out on it recently. Results of mechanical analyses of samples of soil of the typical Aiken loam and the heavy phase follow : MccJianicdl aiuiliises of Ail-ru lotiiii. Nunil:or. Oewrii ticn. Fine p ravel. Coarse sand. Medium sand. Fine sand. Very fine sand. ?ilt. (May. Typical: 573011 . . Heavy phase: 573051 Soil Per cent. 6.4 9.S Per cent. 7.6 10.6 Per cent. 2.4 4.2 Per cent. 9.9 Per cent. 18. S Per cent. ?.9. 3 Per cent. 15.9 : i 9. G S. 4 32.4 25.1 Ol.Y.MI'lC SkUIES. The soils of the Olympic series are brown to rather dark brown; the subsoil, where present, is gray or grayish brown to brown in color, and of similar or somewhat heavier texture and more compact structure than the surface material. Bedrock usually is encountered Avithin 6 feet of the surface, and there are frequent areas of shallow soil marked by rock outcrop. The topography is rolling to steep and hilly, and drainage thorough to excessive. The Olympic soils are residual in origin and are derived from basic igneous and ni(