1. Smd and Gravel, capping the terraces cut in the previous

deposits, and forming slight ridges or eskers in some of the lower levels. It contains on the lower terraces a few shells of Leda and Tellina. At the bottom of this deposit there are seen in places many large boulders of Laurentian and Lower Silurian rocks, resting on the Leda clay below.

2. Leda Clay, exposed in the railway cutting and seen also in the edge of the second terrace. Thickness one hundred

and twenty feet or more. It holds a few large boulders and shells of Leda truncata-the latter uninjured and with the valves united.

3. Boulder clay, or hard gray till, with boulders and stones. Seen in a mill-sluice near the bridge, and estimated at twenty feet in thickness, at this place; though apparently increasing in thickness farther to the westward.

4. Shales of Lower Silurian age, seen in the bottom of the River near the bridge. They are smoothed over, but show no striæ, though they have numerous structure lines which might readily be mistaken for ice-striæ.

To the eastward of the mouth of Trois Pistoles River, the first terrace above-mentioned is brought out to the shore by a projecting point of rock. In proceeding westward toward Isle Verte, it recedes from the coast, leaving a flat of considerable breadth, which represents the lowest terrace seen on this part of the St. Lawrence, and is elevated only a few feet above the sea. This flat is in many places thickly strewn with large boulders, probably left when it was excavated out of the clay. In proceeding westward the first or railway terrace of Trois Pistoles, inland of the flat above mentioned, is seen to consist of Boulder-clay, either in consequence of this part of the deposit thickening in this direction, or of the Leda clay passing into Boulder-clay. It still, however, at Isle Verte, contains a few shells of Leda truncata in tough reddish clay holding boulders.

Rivière-du-Loup and Cacouna.-The country around Cacouna and Rivière-du-Loup rests on the shales, sandstones, and conglomerates of the Quebec and Potsdam groups 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 longitudinal valleys excavated in the softer beds. One of these ridges forms the long reef off 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 Rivière-du-Loup.

The depressions between these ridges are occupied with Postpliocene 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 succession. The oldest member of the deposit is a tough Boulderclay, its cement formed of gray or reddish mud derived from the waste of the shales of the Quebec group, and the stones and boulders 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, but does not appear to be so great as farther to the eastward.

Above the Boulder-clay is a tough clay with fewer stones, and above this a more sandy Boulder-clay, containing numerous boulders, overlaid by several feet of stratified sandy clay without boulders; while on the sides of the ridges, and at some places near the present shore, there are beds 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 Boulder 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 considerable deposits of large shells of Mya truncata, but these are modern, 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 Rivière-duLoup; but I found the most prolific locality to be on the banks. of a little stream called the Petite Rivière-du-Loup, which runs between the ridge behind Cacouna and that of Mount Pilote, and empties into the bay between Rivière-du-Loup and the pier. In these localities I collected and noticed in my paper on this place * more than eighty species, about thirty-six of them not previously published as occurring in the Post-pliocene of Canada.

We have thus at Rivière-du-Loup indubitable evidence of a marine Boulder-clay, and this underlies the representative of the Leda clay, and rests immediately on striated rock surfaces-the striæ running north-east and south-west.

The Cacouna Boulder-clay is a somewhat 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 were being wasted by the waves and currents; and while there is evidence that much of the fine mud worn from them was drifted far to the southwest 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 scaller scale, is now going on in the Gulf. Admiral Bayfield has well 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

• Canadian Naturalist, April, 1805,

more or less by the ice every winter, so that the tracks cleared by the people for launching their boats and building their fishingwears, are in a few years filled up. Wherever such boulders are dropped on banks of clay in process of accumulation, a species of Boulder-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-east, and comparatively little affected by the tides.

The Boulder-clay of Cacouna and Rivière-du-Loup, being at a lower level and nearer the coast than that found higher up the St. Lawrence valley, is probably newer. It may have been deposited after the beds of Boulder-clay at Montreal had emerged. That it is thus more recent, is farther shown by its shells, which are, on the whole, a more modern assemblage than those of the 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 the Boulder-clay is not a continuous sheet or stratum, but that its different portions were formed at different times, during the submergence and elevation of the country; and it must have been during the latter process that the greater part of the deposits now under consideration were formed.

The assemblage of shells at Rivière-du-Loup, is, in almost every particular, that of the modern Gulf of St. Lawrence, more especially on its northern coast. The principal difference is the prevalence of Leda truncata in the lower part of the deposit. This shell, still living in Arctic America, has not yet occurred in the 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 Rivière-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, few specimens were found, and its place is supplied by an allied but apparently distinct species, to be noticed in the sequel, which is still abundant at Gaspé and Labrador, and on the coast of Nova Scotia.

It must be observed that though the clays at Rivière-du-Loup

are more recent than those of Montreal, they are still of considerable 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 level; and in the meantime the high cliffs now fronting the coast must have been cut out of the rocks of the Quebec group.

The order of succession of beds, as seen in the banks of the Little Rivière-du-Loup, may be stated as follows, in descending order:

1. Large Loose Boulders, mostly of Laurentian rocks, seen in the tops of ridges of rock and gravel. One angular mass of Quebec group conglomerate was observed ninety feet in circumference and ten to fifteen feet high. Near it was a rounded boulder of Anorthosite Felspar from the Laurentian, 13 feet long.

2. Stratified sand and gravel resting on the sides of the ridges of rock projecting through the drift. Thickness variable.

3. Stratified sandy clay and sand with Tellina Grænlandica and Buccinum. 10 feet.

4. Gray clay and stones. Rhynconella psittacea, and Terebratulina Spitzbergensis, &c. 1 foot or more.

5. Gray clay with large stones, often covered with Bryozoa and Acorn-shells. Tellina calcarea very abundant, also Leda truncata. 3 feet.

6. Tough, hard, reddish clay, with stones and boulders, passing downward into Boulder-clay, and holding Leda truncata.

6 feet or more.

It was observable that the boulders were more abundant on the south side of the ridges than on the north; and between Rivière-du-Loup and Quebec there are numerous small ridges and projecting masses of rock rising above the clays, which generally show the action of ice on their N. E. sides; while the large boulders lying on the fields are seen to have their longer axes N. E. and S. W.

At the Petite Rivière-du-Loup the surface of the red clay (No. 6 above) was observed to have burrows of Mya arenaria, with the shells (of a deep-water form) still within them.