.%.. v«> IMAGE EVALUATION TEST TARGET (MT-3) /. ^/i 1.0 I.I |50 = IIM 1.8 1.25 1.4 1.6 *» _ f," _ ► VQ <^ /# / 0>^ %'> ^^ -^^ Photographic Sciences Corporalion i. ^^ % rV <^ #x ^9> \ o^ \j fV" 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4503 %"■ m iP MS) WJ.x CIHM/ICMH Microfiche Series. CIHM/ICMH Collection de microfiches. Canadian Institute for Historical Microreproductions / Institut Canadian de microreproductions historiques \ \ V- Technical and Bibliographic Notas/Notas lachniquas at bib!:ographiquas The Institute has attempted to obtain the best original copy available for filming. Features of this copy which may be bibliographically unique, which may alter jny of the images in the reproduction, or which may significantly change the usual method of filming, are checked baiow. D D D n D D D D D n Coloured covers/ Couvertura de coulaur Covers damaged/ Couverture andommagee Covers restored and/or laminated/ Couverture restaurde et/ou peiliculde Cover title missing/ >.e titre de couverture manque Coloured maps/ Cartes giographiques en couleur Coloured ink (i.e. other than b!ua or black)/ Encre de coulaur (i.e. autre que bieue ou noire) Coloured plates and/or illustrations/ Plarconth- western side the same thing can hkewise be (hseerned. hut the (hps seem to he steeper, more nearly approaching the vertical, and continue so for a couple of miles to the southwest, where the lower rock beds become gradually covered up by the over- lying alluvium-like horizontal softer beds rdready noticeil. A couple of miles northeast of the ellipse similar indications show that the rock beds form another nearly ])arallel basin, btu the ridges are more broken up. ruikx<^^^^?-7^Hi^ v^^^^??'^^'*''^^saBiiB?My^^^t^M^yLi jSB^wSSKS^j^^^^^^^'^'^^^^^'^^^^J^^^^^^aB^^^KB^k mS^^^^MS^^^^.4jifm' 1 "'?'r;?^^^^^^P^Ji|lfflJM ^^^fl^Kfl|^uM^^|BBjttHfiKfJW ^^^iS^^^ /-^!^i£^^k^£.i^^^^^^^fw^^^HlHKsfflR9MG^^B ■H^B^^HLSiM^t^^^Ztlv''' " ^rSHHS^'^/i^i ' W 'ff*Tr*-T ^it^B 'fiH^WHiiFfKt JTlWHBnMifflirl WSm/Mlmm^^SWSSlPJmvm^ IHH^^i^H^^^^^HHBK :^^^BBtf!fa <4ni^.^ l^^wScfir'^'slQ ini^HHH^ailSwvi^dR mB^w^B^al^r'i TBB^Ep^^^^MiWl^a ^H^aBiMl^MH^E^iCTX TfT ^c^" ^X"* *3BMSiiil5teiLL^iCT'^ inK^SH^n^T'V I'l.ATK IV. i 1 i 1 < 1 ( t 1 1 I 1 t ( \ May, 18', S.] Geological Structure and Topography. > little basins and saddles. These folds are. to be sure, irr^ larly combined and in many places fractured and crushed i .0 discontinuity. The overlying, more recent, still scft, level- bedded, alluvium-like material of the plains partially masks and obscures the geological structure of the underlying rocks, but is cut through in so many places as not to conceal it alto- gether. In spite of all the irregular crushing and the occa- sional concealment, many of the saddles and basins can be dis- tinctly seen, or without great difficulty discerned, thanks to the mainly favorable circumstances. In the Appalachian region of Pennsylvania the same indu- ence of the geological structure upon the topography is ob- servable on a much larger scale. The successive masses of harder and softer beds are much thicker, the whole series much stronger, stiller and less readily yielding, and the basins and saddles much more extensive. The irregular crushing and breaking of these great folds is less in proportion to the whole, and the result is in the main an aggregation of comparatively simple regular waves. Ijasins and saddles on a grand scale. The topography indicates those large forms in the same general way as the small ones we have been considering in the Punjab, and has been of great service in the study of the geology of Pennsylvania ever since the days of the first State Geological Survey. The varied topographical effects of the long, narrow basin-form and saddle-form were ably discussed by Lesley and H. D. Rogers forty years ago, when the subject was new to geologists. For the comparatively simple conditions of the Appalachians did not exist in most of the European regions where geological work had been done, and the outcrops of the different geological formations and their structure had been traced out more exclusively by means of their fossils, without regard to the topographical indications, that exist mainly in a less obvious degree. The first impression was that the Pennsylvania topography had been produced by an inunense flood of water, an ocean let loose, flowing over the land and carrying away vast ([uan- tities of earth and stones. In those days it was difficult to rid one's self of the idea that great geological changes were almost 360 Lyman. IJ. F. I., mstaniaiicously ])r()(lm-c(l liy treniciulons cataclysms or even Iiy (lowiirii^lit ,sui)CM-iiatural means or miracles. The idea still lingers amon.t;- men not familiar with ^-eolos-ioal matters that snnic stnpendonN topoi^raphical resnlts have been eltected in the t\viidnt all geologists now realize that the scul])tin-ed relief of the monntains and valleys, even where most astonnding. even tlie gorge of the Niagara or the canon of the Colorado, has been accomplished in the lapse of thonsands of _\cai-s ]>y the same agents, chielly rain and stream> of water, that we see still in action abont ns. It is i)laiii that tlie geological indications given bv the snr- fai-c topogra])hy nnist ha\c great \alne of a practical kind, and aid very nnich towards ascertaining both the general snbter- ranean structure and the smaller details of either theoretical iiUerest or economical importance. Jf coal or iron (jre or other valuable mineral is known U) occupy a particular geological horizon, a certain layer in a series of rock beds, such a series, for exam])le, as we have in these Punjab illustrationr-., the jilace of oiUcrop of that horizon or layer, with the useful mineral, may in many cases be recognized merely by means c^f a careful stndy of the topography, and often the general structure, whether that of a basin or of a saddle, may be percei\'ed; even though the surface of the ground may be so covered with loose earth and broken stone as to onceal the dii)S and precise char- acter of the solid rock l>eds below. The Punjab illustrations of the inlluence of the geological structure on the topography are interesting from their show- ing so clearly the small basins and saddles, with freciuentlv \-ery steej) dii)s, but occasionally geinle ones, and with the repeated .alternation of rather thin harder and softer rock I'.eds. partly l)uried under level-bedded, soft, alluvium-like beds, in a region where the rock betis are in the main verv stronfrlv coni])ressed and sharjily folded and often broken and crushed together. The map is a striking example of the excellent geo- logical results of faithful topographical work by surveyors who were no doubt (|uiie unconscious of its ha\ing any signihcance for ij\'( il< >L' A'.