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VII.—On Canadian and Scottish Glacial Geology. By RALPH RICHARDSON, F.R.S.E., Vice-President (Read 19th February 1885.) IN the following paper I desire briefly to state what seem to me to be the leading distinctions between the superficial geology of Canada and Scotland, as w$ll as the points in which the two countries coincide. I shall more particularly refer to the glacial beds of that portion of Canada known as Acadia (that is, Nova Scotia, New Brunswick, and Prince Edward Island), as the section there has been so clearly, carefully, and authoritatively established by our distinguished Honorary Fellow, Principal Sir William Dawson, himself a native of Acadia. Although re­ ferring therefore specially to Acadian glacial beds, I would beg to observe that, so far as I can ascertain, you may with con­ siderable safety apply the description of the superficial geology of Acadia to that of at least the Laurentian district of Canada, embracing the great provinces of Quebec and Ontario. Then with regard to the shells contained in these beds, and to which I shall refer immediately, I had abundant opportunity of verifying them during my recent visit to Canada, the beautifully arranged museums of the Dominion containing collections of glacial shells from the various Canadian beds which amply illustrate this interesting period in the history of the earth. In his well-known work on "Acadian Geology " (2nd edition, 1868, pp. 59 and 76), Principal Dawson gives the following as a typical section of the superficial geology of Acadia, and as in some respects also applicable to Canada and Maine. At the bottom of the section occur Peaty deposits; above them un- stratified Boulder clay; above it, stratified "Leda clay." with marine shells; and lastly, above that, gravel and sand beds, the "Saxicava sand" with marine shells. He considers that the Leda clay indicates deposition in deep water, and the Saxicava sand deposition in shallow water, ancient Gravel ridgeo and beaches being likewise found beside the latter. Such a section as this differs somewhat from typical sections of Scottish Glacial beds. We have in Scotland abundant sections of peat, boulder clay, and gravel and sand, but the attempt has not yet been successfully made to distinguish such and such a Glacial bed as indicating deep-sea conditions, and above it another bed indicating shallow water. On the contrary, the sections exposed in Scotland seem to present everything pile-mile, and not in the orderly fashion exhibited in Acadia. Downloaded from http://trned.lyellcollection.org/ at University of Glasgow on June 27, 2015

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The marine shells in our Scottish beds are all mixed up together regardless, as a rule, of the province (whether Arctic, or British, or both) to which they properly belong; regardless of the depths which they usually tenant; and regardless of the deposit (whether clay, gravel, or sand) in which they are now found- fossil. They are likewise met with at all heights, from the level of the sea to more than 500 feet above it. There are some localities in Scotland where the shells seem to indicate more distinctly Arctic conditions than else­ where; and there are others where deep-sea conditions seem more evident than shallow water. But as yet there has not been sufficient evidence to enable us to group our Fossili- ferous glacial deposits into a deep-water clay, and an over­ lying shallow-water sand. I have recently had the oppor­ tunity of learning the opinion of perhaps the leading authority in Scotland on this subject. Mr David Bobertson of the Glasgow Geological Society, who has made the glacial shell beds of Scotland his special study for many years, wrote me as follows on 5th November 1884:—" As regards the sequence of deposits of gravel, sand, and mud, indicating their respective periods of deposit and deep and shallow water, we must as yet consider this vague and fallacious in many cases; for sand and gravel deposits depend on various circumstances, such as changes of currents, deflections of river mouths, and other local causes,—conditions that are often very misleading." The same remark applies to the difficulty of grouping Boulder erratics in Scotland. Having had the honour to be a member of the Boulder Committee of the Boyal Society of Edinburgh, I have had some insight into this question. We presented our tenth and final Beport to the Society in July 1884, but, after a lengthened investigation, conducted mainly by, our esteemed president, Mr Milne Home, the Convener, the Committee could report no orderly arrangement or definite centres of dispersion of Scottish erratics, and even very few traces of those trainees of Boulders which occur in North America and elsewhere. I understand that the Boulder Committee of the British Associa­ tion hoped to be able to make out and map some system of dispersion of erratics in England, but as yet 1 tegret to think we have no clue to such a system in Scotland. Becurring to Principal Dawson's section, we observe that at its base are placedPeaty deposits. He states, that in Canada peaty de­ posits occur beneath the Boulder clay, and form the lowest Acadian superficial deposit. In Scotland, also, we occasionally find peat very low down in the scale. Mr David Bobertson informs me that in sinking a pit in the neighbourhood of Kilmarnock, peat or peaty mud was found under 50 feet of Boulder clay. A sand-bed, with shells, occurred between the peaty bed of the Downloaded from http://trned.lyellcollection.org/ at University of Glasgow on June 27, 2015

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Boulder elay, whilst another shelly bed occurred beneath the peat (" Trans. Glasgow Geological Society," 1869. Paper by Messrs Craig and Young). This Boulder-clay, however, would probably be the Upper Boulder clay of Professor James Geikie, which is divided from the underlying till by marine sands and gravels frequently containing shells. Again, Mr John Henderson found a bed of peat intercalated in a mass of till resting on Carboni­ ferous rocks at Slateford, near Edinburgh ("Trans. Edin. Geo. Soc./' ii 393). But as a rule, peat overlies the Glacial beds in Scotland, as the following Scottish sections given by Dr Jamieson of Ellon (" Q. J. G. S.," xxi. 185), show :— 1. Near Abernethy, Valley of Tay.—Lowest, sand and gravel; then Peat; then Carse-elay or Estuarine Mud. 2. Also near Abernethy.—Lowest, Boulder clay; then Peat, with remains of trees ; then Estuarine Mud. 3. Blair Drummond, Valley of Forth.—Lowest, Sandstone ; then Glacial beds; then Peat with trees; flien Carse clay; and then again Peat with trees. 4. Estuary of the Ythari, Aberdeenshire.—Lowest, Gneiss; then Boulder clay; then fine Stratified clay and sand; then Peat; and then old Estuarine beds with shells. Dr Jamieson's theory is, that after the Glaciers finally retreated, and Britain formed part of the continent of Europe, the land-surface of Scotland was covered by forests now repre­ sented by submarine forests, and beds of peat with remains of trees. In Scotland, therefore, the peat, as a rule,'follows the beds which furnish evidence of glacial conditions; whilst in Acadia, it precedes them, according to Principal Dawson's section. In so far, there is little or no resemblance between the Acadian and the Scottish Glacial beds. But let us look at points of similarity. In the first place, the facies of the marine shells discovered in„ both countries is very similar. Such marine shells as the following are found as frequently in the Acadian as the Scottish beds, viz., Pecten Islandicus, Mytilus edulis, Leda rostrata, Tellina Groenlandica and calcarea, Mya truneata, Saxicava rugosa, Natica clausa, and Buccinum undatum. All these shells are Arctic, and all are found at high levels in Scot­ land. (Paper and map by author, " Trans. Edin. Geo. Soc," iv. 179.) M In the second place, I gather from Principal Dawson's section, that all the shelly Glacial beds in Acadia occui! above the unstratified Boulder clay, which I take to be synonymous with our Scottish till, our most ancient Boulder clay. Now, all the marine shells in Scotland are likewise found over-lying the till. In some exceptional cases, as in Caithness, they are found Downloaded from http://trned.lyellcollection.org/ at University of Glasgow on June 27, 2015

208 EDINBURGH GEOLOGICAL SOCIETY. mixed up with the till, but the theory which has been advanced to account for this is, that the shells were scoured by ice out of the bed of the North Sea, along with pebbly mud and flag-stone debris. In other cases, discoverers have supposed that they found the shells lying beneath the^till, but afterwards it turned out that they had made a mistake. Thus, in 1850, Mr James Smith of Jordanhill announced that he had discovered shells below the till at Chapelhall, near Airdrie, Lanarkshire, 510 feet above the sea. But in 1865, Dr Crosskey, in a paper read before the Geological Society of London (" Q. J. G. S.," xxi. 219), said, that on examination of the Chapelhall section, he had formed the opinion that the Arctic shell-bed there w%s not (as Mr Smith supposed) below, but above the till, thi bed which Mr Smith termed "till" being probably a clay of later deposit than till. Again, Dr Crosskey himself was once apparently as certain that he had discovered shelly clay beneath till at Tangy Glen, near Campbeltown, 130 feet above the sea (" Trans. Geoi Soc, Glasgow,- iv. 134). I do not know what his opinion concerning this section may now be, but his collaborateur, Mr David Bobertson of Glasgow, wrote me in November 1882 as follows:— " I may mention that since the discovery of the Tangy Glen deposit, I have doubts, in this instance, that these clays are not lying in the position that they were first laid down, seeing that the shelly deposit is lying at the bottom of a deep glen cut out by the water that it drains. It appears most probable that the shell-bearing clay is covered by a landslip of the Boulder clay, such slips being of common occurrence in such situations." Last summer I had the pleasure of visiting Mr David Robertson at Uddingston, and of seeing his splendid collections of Glacial shells from the Clyde, Sweden, &c. He corroborated, in the course of conversation, the statement made in the letter I have just quoted, that he and Dr Crosskey were mistaken in suppos­ ing that at Tangy Glen the shelly clay occurred beneath the till At the same time he said he had heard from a reliable authority that a shell-bed had, in another part of Scotland, been discovered beneath the till. Mr Robertson had not seen this section how­ ever, although he had every confidence in the observer; and he admitted that if such a section did exist, it was the only one of the kind he knew. On the whole, the evidence in Scotland is in favour of Till being the first deposit of Glacial Age, followed by clay, sand, and gravel containing marine shells of a greater or less Arctic facies. These are the "interglacial beds" of Glacial geologists, and they are followed by an Upper unstratified Boulder clay formed apparently as the Till or Lower unstratified Boulder clay was. Take such a 'section as that discovered in 1881 (and com- Downloaded from http://trned.lyellcollection.org/ at University of Glasgow on June 27, 2015

CANADIAN AND SCOTTISH GLACIAL GEOLOGY. 209 niunieated to our Society by Mr James Fraser, C.E., Inverness), at Drumnioreof Clava, some seven miles due east of the town of Inverness. The most remarkable circumstance connected with this discovery is that Mr Fraser found marine shells at a height of 500 feet above the level of the sea, which, with the exception of the discovery already mentioned at Chapelhall, near Airdrie (510 feet), is the highest level at which shells have been found in Scotland. I may add that the shells discovered at Clava included four Arctic and not British living species, and five both British and Arctic living species (" Trans/Edin. GeoL Soe.," voL iv. pp. 136 and 185.) With regard to the nature of the section discovered by Mr Fraser, he found, going from top to bottom, firstly, 50 feet of soil and gravel, and Boulder clay; then 20 feet of stratifiedtfine sand; and lastly, the said shell-bed, which consisted of blue clay, and the bottom of which was not reached, although a depth of 7£ feet had been passed through. The depth of the section actually attained was thus 77| feet. If the Glacialists' theory and the evidence of other Scottish shell-beds are reliable, Mr Fraser, if he had dug deeper, should have found the till below the shelly clay, the Boulder clay previously mentioned in his section being the Upper and not the Lower Boulder clay of Scotland. The belief in earlier and later Boulder clays is of long standing in Scotland, having been advocated by that well-known Geologist, the late Professor John Fleming. Although, as I have pointed out, the Glacial beds of Canada and Scotland differ in some respects^ there can be little doubt that in their cardinal features they coincide. That great mass of unstratified clay which we in Scotland call Till, exists in Acadia as well; and doubtless it perplexes the Geologists of the New World, as it still does those of the Old, to account for the origin of the Till with a feeling of perfect certainty and satisfaction. The meeting of the British Association in Edinburgh in 1850, at which Professor Fleming^Hugh Miller, and others were present, seems to have broken up without solving the question of the origin of the Boulder clay, although Hugh Miller read a paper upon the subject, and Professor Fleming (according to James Nasmyth's Autobiography) said he could not sleep at night for thinking of it. At the meeting of the British Association held in Montreal in August-September 1884, we were favoured by the presence of the foremost champions of the two leading opposing schools, Principal Dawson and Professor James Geikie, but I cannot say that any advance was made in solving this great question. Although the majority of North American Geologists present in Section C (Geology) seemed in favour of the view originally promulgated by Agassiz, that an ice-sheet once covered the northern halves of Europe and America, Principal Sir Downloaded from http://trned.lyellcollection.org/ at University of Glasgow on June 27, 2015

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Wm. Dawson adhered firmly to his opinion that we nrast look to submergence and floating ice and local glaciers, for the key to unriddle this great mystery. Sir William's masterly address, delivered at Minneapolis in August 1883,1 as President of the American Association, gives us the views he has formed regard­ ing the glaciation of the north-west of America, being what he calls "the great interior plain of Western Canada between the Laurentian axis on the east, and the Eocky Mountains on the west," which is "700 miles in breadth and is covered with glacial drift, presenting one of the greatest examples of this deposit in the world." "Perhaps," said Sir William Dawson, "the most remarkable feature of the region is that immense series of ridges of drift piled against an escarp­ ment of Laramie and Cretaceous rocks at an elevation of about 2500 feet, and known as the 'Missouri Coteau.' It is in some places 30 miles broad, and 180 feet in height above the plain at its foot, and extends north and south for a great distance; be­ ing in fact the northern extension of those great ridges of drift which have been traced south of the Great Lakes, through Penn­ sylvania and New Jersey, and which figure on the Geological maps as the edge of the continental glacier,—an explanation obviously inapplicable in those western regions where they attain their greatest development. It is plain that in the north it marks the western limit of the deep water of a glacial sea, which at some periods extended much farther west, perhaps with a greater proportionate depression in going westward, and on which heavy ice from the Eocky Mountains was borne east­ ward from these mountains by the prevailing westerly winds. We thus have in the west on a very wide scale the same pheno­ mena of varying submergence, cold currents, great ice-floes, and local glaciers producing icebergs, to which I have attributed the Boulder clay and Upper Boulder drift of Eastern Canada." From this you will see that Sir Wm. Dawson still champions the glacial-sea theory as opposed to the continental ice sheet theory; and that he attributes the formation of Boulder clay to the action of that sea. The Boulder clay which extends for a 100 miles east of the Eocky Mountains rests, he says, upon gravel not glaciated. The Boulder clay itself is, he adds, largely made up of local debris, but it contains many glaciated boulders and stones from the Laurentian region to the east, and also smaller pebbles from the Eocky Mountains. He accounts for this by supposing that, at the time of its formation, there must have been driftage of large stones for 700 miles or more from the east, i.e., from the Laurentian region, and also driftage of smaller stones from a less distance on the west, i.e.9 from the

1 See also Principal Dawson's paper on the Geology of the line of the Cana­ dian Pacific Railway, read before the Geological Society of London in April 1884 ("Q, J. G. xl. 384.) Downloaded from http://trned.lyellcollection.org/ at University of Glasgow on June 27, 2015

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Eocky Mountains. Laurentian boulders have, he says, been discovered on the flanks of these mountains, at a height of more than 4600 feet above the sea; from which we may infer the great depth of the glacial sea, for the mountains must have been its shore-line. Now, all this is of course quite contrary to the ice-sheet theory which Agassiz adopted to account for the glacial pheno­ mena of North America. His idea of the formation of Boulder clay was, that the ice-sheet had formed it by grinding the rocks over which it travelled. "The glacier,'' he said, "was God's great plough; and when the ice vanished from the face of the land, it left it prepared for the hand of the husbandman. The hard surface of the rocks was ground to powder, the elements of the soil were mingled in fair proportions, granite was carried into the lime regions, lime was mingled with the more arid and unproductive granite districts, and a soil was prepared fit for the agricultural uses of man." By whatever means it was produced, there can be no question that the soil of the vast North-West of Canada, the region which either ice-sheet or glacial sea certainly covered, is, generally speaking, peculiarly adapted for the cultiva­ tion of wheat; although as I pointed out in a Paper which I read before this Society in 1879 ("Trans.," vol iii. p. 262), climate has more to do with agriculture than geology; and as Mr Vernon Smith remarked, "the fact, established by climatologists, that the cultivated plants yield the greatest products near the northernmost limit at which they grow, is fully illustrated in the productions of the Canadian territories." In conclusion, I must say a few words in explanation of the Canadian Government's map of the great Canadian North-West, which I exhibit, and which was freely distributed among those attending the Geographical Section at Montreal last August, the particular meeting at which I received it being that assem­ bled to hear the famous Arctic explorer, Lieutenant Greely, give an account of his recent most arduous expedition. I have marked upon this map the superficial geological features of the country, as detailed in the sketch map. accompanying Principal Dawson's Paper read before the Geological Society of London last year (" Q. J. G. S.," August 1884). You first observe on it, to the right, the Laurentian axis. Passing westwards, and to the south of Bainy Biver, occurs the " boulder drift area of Lake Superior." Then, on both sides of the Bed Biver, and extending north­ wards along the west side of Lake Winnipeg, we have the " Bed Biver Prairie," a lacustrine deposit, the site of the so- called " Lake Agassiz," consisting of very fine silt with over­ lying black vegetable soil. This "Eed Eiver Prairie" (in which Winnipeg city is situated) is about 800 feet above the level of the sea. It constitutes the first and lowest level of prairie land, the land to the west rising in two great steps or escarpr Downloaded from http://trned.lyellcollection.org/ at University of Glasgow on June 27, 2015

212 EDINBURGH GEOLOGICAL SOCIETY. ments to the base of the Rocky Mountains; the tract imme­ diately to the west of the " Red River Prairie " being called the second prairie level (the towns of Brandon and Regina are on this level); whilst further west we find the third prairie level (the towns of Medicine Hat and Calgary are on this level). Thus gradually we reach the base of the Rocky Mountains, the prairie land ending at a height of about 4200 feet above the sea, or 3400 feet above the level of the Red River prairie. The "second prairie level," immediately to the west of the Red River prairie, is covered with " travelled boulders, associated either with Boulder clay or overlying sands and gravels." It extends as far west as the celebrated "Grand Missouri Coteau," 400 miles west of Winnipeg city. This giant ridge is described by one school of Glacialists as the terminal moraine of a great continental glacier or ice-sheet, and by Principal Dawson as " the margin of an ancient glacial sea." It extends southwards into the United States, and consists of " thick beds of imper­ fectly stratified clay," with many Laurentian boulders, and above the clay stratified gravels also with large boulders. Finally, we reach the " third prairie level," which takes us to the higher plains at the base of the Rocky Mountains, some 4200 feet above the sea. This upper prairie plateau, extending from the Grand Missouri Coteau to the Rocky Mountains, has not as a rule many boulders on its surface, yet erratics occasionally occur, consisting of " Laurentian gneiss, Huronian schists, and yellow Silurian limestone, all," says Principal Dawson, " derived from the eastern side of the plains, some of the boulders of Lauren­ tian gneiss being of great dimensions." The buffalo, he remarks, which is now extinct on these plains, used some of these great boulders as " rubbing-stones," as the basin-shaped depressions round the boulders, formed by the feet of these animals, still testify. Again, at the height of from 4200 to 4660 feet, on the eastern slopes of the Rocky Mountains, Laurentian boulders and fragments of limestone from the eastern Palaeozoic beds have been found. Principal Dawson considers that they evidence " a driftage of at least 800 miles." He says—" These pheno­ mena are explicable on the hypothesis of a glacial sea of varying depth, but not on land glaciation, which would also be inappli­ cable in a region necessarily of so small precipitation of moisture, and occupied by soft deposits, so little suited to the movement of glaciers. There is, nevertheless," he adds, " good evidence of the action of glaciers on a large scale, in certain portions of the glacial period, both on the Rocky Mountains and on the Lau­ rentian hills and table-lands to the east." As to the underlying rocks of the North-West, they are chiefly Cretaceous and Ter­ tiary, and several outcrops of Cretaceous coals occur along the eastern base of the Rocky Mountains, and cross the railway line to the west of the town of Medicine Hat.