IMAGE EVALUATION TEST TARGET (MT-3) A ^ >^ // \ (moaning "CON- TINUED"), or tha symbol y (moaning "END"), whichavar appliaa. Un daa aymbolas suivants apparattra sur la darniAra imaga da chaqua microficha. salon la caa: la symbola — ^ signifia "A SUIVRE". la symbols V signifia "FIN". Maps, platas. charts, ate may ba filmad at diffarant raduction ratioa. Thoaa too larga to ba antiraly includad in ona axposura ara filmad baginning in tha uppar laft hand comar, laft to right and top to bottom, aa many framaa aa raquirad. Tha following diagrama iliustrata tha mathod: Laa cartaa, planchaa, tablaaux, ate, pauvant Atra filmia A daa taux da reduction diffArants. Lorsqua la documant aat trop grand pour Atra raproduit an un saul clichA, 11 aat film* A partir da I'angia aupAriaur gaucha. da gaucha A droita, at da haut an baa. an pranant la nombra d'imagas nAcassaira. Las diagrammaa suivants illustrant la mAthoda. 32X 1 2 3 1 2 3 : 4 5 6 ) I 1 (From The Canadian Naturalist, for April, 1865.) NOTES ON POST-PLIOCENE DEPOSITS AT RIVIERE-DU-LOUP AND TADOUSSAC. By J. W. Dawson, LL.D., F.R.S., F.G.S., Principal of McGill College. In looking over, last winter, some of the collections made by Prof. Bell, of Kingston, when engaged in the service of the Geo- logical Survey of Canada, I was struck with a small collection of Post-pliocene shells from Rivi6re-du-Loup,* as presenting a some- what singular grouping of species ; and having a few holiday weeks to spend at Cacouna, I determined to ransack thoroughly the de- posits which had aflForded these specimens. The country around Cacouna and Rivi^re-du-Loup rests on the shales, sandstones, and conglomerates of the Quebec group of Sir W. E. Logan. As these rocks vary much in hardness, and are also highly inclined and much disturbed, the denudation to which they have been subjected has caused them to present a somewhat uneven surface. They form long ridges running nearly parallel to the coast, or north-east and south-west, with intervening longi- tudinal valleys excavated in the softer beds. One of these ridges forms the long reef oflF Cacouna, which is bare only at low tide ; another, running close to the shore, supports the village of Cacouna; another forms the point which is terminated by the pier; a fourth rises into Mount Pilote; and a fifth stretches behind the town of Rivi(^re-du-Loup. • See Geology of Canada, p. 921, where, however, only a portion of the gpocies collected are mentioned. 2 The depressions between these ridges are occupied with Post- pliocene deposits, not so regular and uniform in their arrangement as the corresponding beds in the great plains higher up the St. Lawrence, but still presenting a more or less definite order of suc- cession. The oldest member of the deposit is a tough boulder- day, its cement formed of gray or reddish mud derived from the waste of the shales of the Quebec group, and the stones and boul- ders with which it is filled partly derived from the harder members of that group, and partly from the Laurentian hills on the opposite or northern side of the river, here more than twenty miles distant. The thickness of this boulder-clay is, no doubt, very variable, and could not be ascertained in the neighborhood of Cacouna ; but at He Yerte it forms a terrace fifty feet in height. Above the boulder-clay, where it has not been bared by denu- dation, there occurs a dark gray, soft, sandy clay, containing numerous boulders, and above this several feet of stratified sandy clay without boulders; while on the sides of the ridges, and at some places near ihe present shore, there are bed» and terraces of sand and gravel, constituting old shingle beaches apparently much more recent than the other deposits. All these deposits are more or less fossiliferous. The lower boul- der-clay contains large and fine specimens of Leda truncata and other* deep-water and mud-dwelling shells, with the valves attached. The upper boulder-clay is remarkably rich in shells of numerous species; and its stones are covered with Polyzoa and great Acorn- shells {Balanus Hameri), sometimes two inches in diameter and three inches high. The stratified gravel holds a few littoral and sub-littoral shells, which also occur in some places in the more recent gravel. On the surface of some of the terraces are con- siderable deposits of large shells of Mi/a truncata ; but these are modem, and are the ' kitchen-middens ' of the Indians, who in former times encamped here. Numbers of Post-pliocene shells may be picked up along the shores of the two little bays between Cacouna and Bivi^re-du- Loup ; but I found the most prolific locality to be on the banks of a little stream called the Petite Rivi6re-du-Loup, which runs between the ridge behind Cacouna and that of Mount Pilote, and empties into the bay between Rivi6re-du-Loup and the pier. In these localities I collected eighty-four species, about thirty-six of them not previously published as occurring in the Post-pliocene of Canada. A list of these fossils is appended to this paper ; and 8 in connection with it I would dcHiro to inuke some general remarks on the features of these interesting deposits. We have here an indubitable instance of a marine bouldcr-clay. I have observed fossiliferous boulder-clays at Murray Bay, St. Nicholas, and Cape Elizabeth, but the example afforded at Cacouna and its vicinity is more clear and instructive ; and there is also evidence that the surface under the boulder-clay is polished and striated, the direction of the striaa being north-east and southwest, or that of the St. Lawrence valley.* The Cacouna boulder-clay is a deep-water deposit. Its most abundant shells are Leda truncata, Nucula tenuis, and Tellina proxima, and these are imbedded in the clay with the valves closed, and in as perfect condition as if the animals still inhabited them. At the time when they lived^ the Cacouna ridges must have been reefs in a deep sea. Even Mount Pilote has huge Laurentian boulders high up on its sides, in evidence of this. The shales of the Quebec group wei^ being wasted by the waves and ourrents ; and while there is evidence that much of the fine mud worn from them was drifted far to the south-west to form the clays of the Canadian plains, other portions were deposited between the ridges, along with boulders dropped from the ice which drifted from the Laurentian shore to the north. The process was slow and quiet ; so much so that in its later stages many of the boulders became encrusted with the calcareous cells of marine animals before they became buried in the clay. No other explanation can, I believe, be given of this deposit ; and it presents a clear and convincing illustration, applicable to wide areas in Eastern America, of the mode of deposit of the boulder-clay. A similar process, though probably on a much smaller scale, is now going on in the Gulf. Admiral Bayfield has veil illustrated the fact that the ice now raises, and drops in new places, multi- tudes of boulders, and I have noticed the frequent occurrence of this at present on the coast of Nova Scotia. At Cacouna itself, there is, on some parts of the shore, a band of large Laurentian boulders between half tide and low-water mark, which are moved more or less by the ice every winter, so that the tracks cleared by the people for launching their boats and building their fishing- wears, are in a few years filled up. Wherever such boulders are dropped on banks of clay in process of accumulation, a species of * South 55° west mag., near Cacouna. bouldcr-clay, similar to that now seen on the land, must result. At present such materials are deposited under the influence of tidal currents, running alternately in opposite directions ; but in the older boulder-clay period, the current was probably a steady one from the north-oast, and comparatively little affected by the tides. The bouldor-olay of Caoouna and lliviircdu-Loup, being at a lower level and nearer the coast than that found higher up tho St. Lawrence valley, is probably newer. It may have been deposited after tho beds of boulder-clay at Montreal had emerged. That it is thus more recent, is further shown by its shells, which are, on tho whole, a more modern assemblage than those of tho Leda clay of Montreal. In fossils, as well as in elevation, these beds more nearly resemble those on the coast of Maine. It would thus appear that tho boulder-clay is not a continuous sheet or stratum, but that its different portions were formed at different times, during tho submergence and elevation of the country ; and it must have been during tho latter process that the greater part of the deposits now under consideration were formed. The assemblage of shells at Riviire-du-Loup is, in almodt every particular, that of the modern Gulf of St. Lawrence, more cspc- ciidly on iis northern coast. The principal difference is the pre- valence of Leda truncata in the lower part of the deposit. This shell, still living in Arctic America, has not yet occurred in tho Gulf of St. Lawrence, but is distributed throughout the lower part of the Post-pliocene deposits in the whole of Lower Canada and New England, and appears in great numbers at Ilivi6re-du- Loup, not only in the ordinary form, but in the shortened and depauperated varieties which have been named by Reeve L. siliqua and L. sulcifera. Of Astarte Laurentiana, supposed to be extinct, and which occurs so abundantly in the Post-pliocene at Montreal, only one valve was found, and its place is supplied by the allied but appa- rently distinct species, A. conipressa, which is still abundant at Gaspd and Labrador, and on the coast of ^I'ova Scotia. This exchange of A. Laurentiana for A. compressa is on these coasts an unfailing evidence of less antiquity. A study of the varietal forms under which common species occur, also leads to the same conclusion as to the less comparative antiquity of these beds ; but this is a very curious and intricate question, on which I have accumulated a great nuniber of f^iots which I propose to publish at a future time. t It must be observed that though the olays at Bivi6rc-du-Loup are more recent than those of Montreal, they are still of consider- able antiquity. They must have been deposited in water perhaps fifty fathoms deep, and the bottom must have been raised from that depth to its present levul ; and in the meantime the high cliffs now fronting the coast must have been out out of the rooks of the Quebec group. The order of succession and characteristic fossils seen on the banks of the Petite Rivi6re-du-Loup may be stated as follows, in descending order : 1. Gravel seen on sides and tops of ridges. 2. Stratified sand and clay — Bmcinuni undutum and Tellina Grcvnlandlca. 3. Bluish sandy clay, stones, and boulderb, Balanm Humeri, Rhynchonella pdttacea, Fecten Islandicua, Leda tenuisid' cata, L. minuta, Tellina calcarea, Astarte compressa, Saxicaoa rugosa, Actnoea coeca, Scalaria Grcenlandica, Natica clatisa, Bucclnum scalarl/orme, Bryozoa on stones, Foramini/era, &c., &o. 4. Stiff reddish clay with stones and boulders — Leda truncata, L, Umatula, Nucula tenuis, Tellina calcarea, &c. At Tadoussac, opposite to Caoouna, where the underlying for- mation is the Laurentian gneiss, the Post-pliocene beds attain to great thickness, but are of simple structure and slightly fossiliforous, The principal part is a stratified sandy clay with few boulders, except in places near the ridges of Laurentian rooks. This forms high banks eastward of Tadoussac. It contains a few shells of Tellina Grcenlandica and Leda truncata. It resembles No. 2 of the above sectional list, and has also m^- ■i of the aspect of the Leda clay, as developed in the valley of the vtawa. On this clay there rest in places thick beds of yellow sand and gravel. At Tadoussac these deposits have been cut into a succession of terraces which are well seen near the hotel and old church. The lowest, near the shore, is about ten feet high ; the second, on which the hotel stands, is forty feet; the third is 120 to 150 feet in height, and is uneven at top. The highest, which consists of sand and gravel, is about 250 feet in height. Above this the country inland consists of bare Laurentian rocks. These terraces have been cut out of deposits, once more extensive, in the process of elevation of the land ; and the present flats off the mouth of the Saguenay, would form a similar terrace as wide as any of the • m 6 others, if the country were to ozporienco another elovatory move- ment. On the third terrace I ohscrved a few largo Laurentiaii houlders, and some pieces of rod and gray shale of the Quebec group, indicating the action of coast-ice when this terrace was out. On tho higher terrace there were also a few boulders ; and both terraces are capped with pebbly sand and well rounded gravel, indicating tho long-continued action of the waves at the levels which they represent. LIST 0¥ FOST-PLIO0£N£ FOSSILS FOUND AT RIVIERE-DU-LOUP AND CAOOUNA. Those marked tkus * have not previously been noticed as occurring in the Canadian Post-pliocene. rORAHINIFERA. Polymorpbina lactea, Adams. Nonionina Scapha, F. and M., and var. Labradorica, Dawson. Polystomella striatopanctata, F. and M. Biloculina ringens? Lam. EntoBolenia costata, WilliamBon. * Truncatulina lobulata, W. and T. * Rotalina? turgida, Williamson. XoTB. — Since the publication of my former list of Foraminifera from the Post-pliocene of Canada (Can. Nat., vol. ir, 1859), I have found at Montreal, Nonionina scapha F. and M., Dentalina pyrula D'Orbigny, and Orbulina universa D'Orbigny. Messrs. Parker and Jones have also kindly revised my former list, and concur in all the determinations, with the exception of Polystomella umbilicalulaf which they refer to P. striatO' punctata, and Bulimina auriculata Bailey, which they refer to B. pyrula D'Orbigny. PORIFBRA. * Halichondria — Silicious spicules. BOHINODERHATA. Echinus granularis, Say. POLYZOA. •L •L, L •L Lepralia Belli, Dawson. L. pertusa, Thompson. producta, Packard. trispinosa, Johnston. hyalina, Fabr. ventricosa, Hassel. Diastopora obclia, Johnston. Tubulipora flabellaris ? Johnston. Hippothoa expansa, Dawson. H. catenularia? Johnston. * Eschura elegantula, D'Orbigny. * Oelleporaria lurcularii, Packard. * Myriozoum subgracile, D'Orbigny. * Heteroporella radiata ? * Alecto. * Membranipora Lacroixii, Busk. BRAOHIOPODA. Rhynchonella psittacea, Gm. * Terebratella Labradorensis, Sow. LAHELLIBRANOHIATA. Pecten Islandicua, Chemn. Leda trunoata, Brown, and vara, siliqua and sulcit'era. * L. tenuisulcata, Oouthouy, (pernula, Wood). L. minuta, Mull, (caudata, Don.). * L. limatula, Say. Nucula tenuis, Mont., (rar. ezpansa). * Modiolaria discors, Linn. M. nigra, Qray. > Mytilus edulis, Linn. * Cardium Dawsoni, Stimpson. * Astarte compressa, Mont. (A. Banksii, Leacb). A. Laurentiana, Lyell. Tellina Groenlandica, Beck. . ^ T. prozima, Brown. T. (Macoma) inflata, Stimpson. Mya arenaria, Linn. M. truncata, Linn., var. Uddevallensis. * Panopaea Arctica, Gould. (P. Norvegica?). Sazicara rugosa, Linn., and var. Arctica. * Lyonsia arenosa, Moll. NoTi.— Large suites of specimens from Rividre-du-Loup enable me to determine with certainty that Leda tenuisulcata Couthouy, L. pemula MuUer, (& Wood, English Crag,) and L. Jacksoni Gould, are rarleties of one species ; that Saxicava Arctica is merely a variety of S. rugosa ; and that Leda tiliqua and L. sulcifera of Reeve are varieties of L, trun- cata, which is identical with L. Portlandica Gould. GASTEROPODA. * Cylichna nucleola. Reeve. Acmcea (Lepeta) caeca. Mull. Gemoria Noachina, Linn. * Adeorbis costulata? Margarita helicina, Fabr., (Arctica). * M. cinerea, Couth. Littorina palliata. Say. * L. rudis, Mont. Scalaria Groenlandica, Perry. / 1' 8 Menestho albula, Moll. * Turritella orosa, Couth. NaticA clausn, Sow. N. Groonlandica, Mull. * N. catcnoidos? Wood. Bola harpularia, Oould, (Woodiann, Moll.). * B. violttcea, Migh. * 13. docusaata, Couth. * U. turricula, Mont. 13. rufa, Qould, (pyratnidalis). Bucclnuni undatum, Linn., and var. Labrailorcnse, Reeve, * B. glaclulc, Linn. * B. acalarifurmc, Moll. * B. cretaccum, Reeve. Fuaus tornatus, Oould, and rar. despcctus, Linn. * Trophon clathratum, Linn. T. scalariforme, Qould. Trichotropis borcalis, B. and S. NoTK.— I regard B, Labradorcme as merely a variety of B, undatum peculiar, lilce the oval or almond-shaped variety of Mytilus edulis, to the mouths of rivers. The species which I have named B. crelaceum is certainly distinct, but I am by no means sure that it is really B. crdit- ceum of Reeve. B. glaciale is common at Montreal and at St. Nicholas ; but the specimens from Rlviore-du-Loup enabled me for the first time to recognize it. ANiMTL&TA. * Spirorbis nautiloidcs, Lam. S. vitrea, Stimp. * S. sinistrorsa, Mont. * S. quadrangularis, Stimpson. CRUSTACEA. Balanus Haracri, Asc, var. Uddcvallensis. B. porcatus. Da Costa. B. crenatus, Brug. Cytlieridea Mulleri, Mun. * Hyas coarctata, Leach. Of the above species, Panopaa Norvcgka, Fusus tornatus, Lcda truncata, L. temdsulcata, Astni-te comprcssa, Mytilus edulis, Mi/a arenaria and Littorina palliata, had been collected at Riviere- du-Loup, by the officers of the Survey, previous to my visit. Mcsodcsma Jauresii had also been collected from littoral gravels east of Caeoujin, but was not met with by me.