Mississippi Valley, to 230 feet on the coast of Maine, and to 500 feet at Montreal and in the valley of the Ottawa River. The question of a succession of Glacial epochs has narrowed itself down in America to the question whether or not there have been two epochs, or one epoch, with minor halts in the recession of the ice. So far as my own observation goes, and it has been extensive, the complete separation between the epochs does not seem to be proved. The forest beds are all pretty well towards the southern part of the area, and are many of them probably pre-Glacial, while others are of such a nature that they might have accumulated in a comparatively brief episode of oscillation of the ice front. The terminal moraine of what is called the Second Glacial epoch, which stretches with a good degree of continuity from the Atlantic to the Mississippi, may well enough be regarded as a moraine of retrocession, of which there are numerous other instances, on a smaller scale, both north and south of this. 5. On the Evidences of Glacial Action in Pembrokeshire, and the Direction of Ice-flow. By HENRY HICKS, M.D., F.R.S., Sec. Geol. Soc. The occurrence of ice-scratched rocks and of northern erratics in north-west Pembrokeshire has already been mentioned by the author, but in this paper he brings forward much additional evidence to show that, during the glacial period, a great thickness of land-ice must have passed over Pembrokeshire. The glacial stria which are so well preserved under the drift along the northwest coast, especially at Whitesand Bay, show that the ice travelled over that area mainly from a north-western direction. The presence of erratics from North Wales and from Ireland would tend to the conclusion that glaciers from these areas coalesced in St. George's Channel, and that the ice which overspread Pembrokeshire was derived from both of these sources, as well, probably, as from a flow extending down the channel from more northern areas. Although there are in the district many northern erratics, notably a large boulder of granite and another of picrite, which the author found on Porthlisky farm, two miles south-west of St. David's, yet by far the majority are of local origin and can be traced back to the parent rocks. The great igneous masses which now form such conspicuous hills along the north coast yielded most of the boulders, many of very large size, which are so freely spread over the undulating land reaching to the coast of St. Bride's Bay. There are clear evidences to show that this bay was itself overspread by a great thickness of drift from these hills. The intervening pre-glacial valleys were also filled by this drift, and the plains and rising grounds up to heights of between 300 and 400 feet still retain evidences of its former presence, and many perched blocks. Excellent sections of unstratified drift, containing large ice-scratched boulders, are exposed in Whitesand Bay, and a thickness of several feet of an irregularly stratified sand was, some time since, exposed under the boulder clay on the east side of the bay. Chalk flints have been found at heights of over 300 feet, probably having been brought from Ireland. The picrite boulder already referred to has been shown by Professor Bonney to resemble masses of that rock exposed in Carnarvonshire and Anglesea, and the granite boulder, which before it was broken must have been over 7 feet in length and 3 to 4 feet in thickness, is identical with a porphyritic granite exposed in Anglesea, but not found anywhere in Pembrokeshire. The evidences, therefore, which go to prove that Pembrokeshire was buried under an ice-sheet that must have spread southwards into the Bristol Channel, are, the presence of many northern erratics, both as perched blocks and in drifts at heights above 300 feet, ice-scratched, smoothed and polished rock surfaces, and, in places, much crushing and bending of some of the strata; also great dispersions of boulders from igneous rocks on the north coast in a south-west direction, and some well-marked examples of 'crag and tail.' 6. Note on Boulders at Darley, near Matlock, Derbyshire. By HERBERT BOLTON, Assistant Keeper, Manchester Museum. During the excavation for a small lake close to the Midland Railway Station at Darley, near Matlock, a cluster of fifteen boulders was exposed, the size of several being sufficient to justify an examination. The size of the largest boulder was 10 feet x 6 feet x 6 feet. The boulders lay in a bed of boulder clay which had a thickness of nine feet. The upper part of the clay was of a strong yellow colour and very stiff. Below, the colour varied from yellow to brown and red, and pockets of sand were com mon. Only two boulders were well rounded, the rest being sub-angular on their upper half, and fairly angular on the lower. All the boulders consist of gritstone identical in character with the Chatsworth grit of the adjoining hills. No striations occur on the boulders, but this may be due to the original surface having crumbled away. A series of parallel and shallow grooves occurs on the side of the largest boulders, and a deep hollow has been scooped out of its southern face. The major axis of the undisturbed boulders was approximately north and south, the general direction for the cluster being 8° west of north. The blocks were arranged in the order of their weight in a north to south direction. The clay was found to rest upon a deposit of the nature of river gravel. The writer is of opinion that the clay is redistributed boulder clay brought down from the adjoining heights, and that the boulders were brought down at the same time from the line of outcrop of the grit. He is led to this conclusion by the local character of the boulders, the almost total absence of foreigners, and the character of the clay. The red and brown colour of the latter at its base seems to show that oxidation of the contained iron has proceeded for a longer time than in the case of the uppermost clay. This would be expected if the clay was redistributed, for the basement mass of clay must have been the superficial clay of the heights. The enclosed sand would also indicate the complete disintegration of boulders of gritstone, &c., whilst the clay was in its primary position. The amount of disintegration which has taken place since redistribution is marked by the crumbling surface of the large boulders. The general direction of the boulders may be explained by noting that the river flows from north to south. 7. Notes of a Section of Drift at Levenshulme, Manchester. In the construction of a new railway between Chorlton-cum-Hardy and Fairfield a good opportunity was afforded of studying the effects of land-ice. The part of the cuttings particularly observed was that extending from Fallowfield almost to the L. and N.-W. Railway at Levenshulme, in a line almost accurately from west to east. Throughout the whole distance the solid geology was displayed with a covering of boulder clay. The rocks consisted in descending sequence (and from west to east) of triassic pebble beds (fault), Permian marl, Permian sandstone, and upper coal measures containing several beds of Ardwick limestone (see Brockbank and De Rance, Mem. Manch. Lit. and Phil. Soc.,' 4th Series, Vol. iv.). The triassic rocks when soft were much mangled and crushed at their contact with the drift; but in places, nearly horizontal intrusions of boulder clay were interposed between the bedding. These intrusions always entered from the west. At one point the triassic beds rose to within about 2 feet of the top of the cutting, the ground being nearly level. At the fault blocks of triassic rocks were dragged over on to the Permian marls. The marls were greatly mangled, and some erratics of large size (andesites, &c.) were involved in their mass. At the base of the marls a coarse bed of hard breccia occurred and its surface was striated from N. 65° W. It was observed that this surface was about 16 feet lower than the triassic sandstone, and therefore the striæ could not have been produced by floating ice, for ice which could clear the ridge to the westward could not ground at a lower level. The bands of Ardwick limestone had been much ice-worn, and from each outcrop a long train of boulders stretched away to eastward. A large boulder of coal measure sandstone (not local) lay embedded in the base of the boulder-clay, and having lodged against its eastern end a large mass of Ardwick limestone derived from an outcrop to the westward. The upper surface of the sandstone boulder was scratched from N. 50° W. This stone had probably been dragged by land-ice across the limestone, and had torn off a mass which in a transit of 50 yards brought it to a stand, tearing it out of the ice which moved on and glaciated the upper surface of the boulder. Fragments of each formation were carried to eastward of the parent mass, but never to westwards. Several large erratics were observed and, with one exception, all had their long axes in approximately the same direction, viz.-a few degrees north of west. The exceptional direction was about N. 20° W. The author is of opinion that the agreement between the direction of (1) the boulder-transportal; (2) the intrusions of boulder-clay; (3) the orientation of large boulders; and (4) of ice-scratches upon rock-surface and the upper surfaces of boulders, constitutes proof of the action of land, and not floating, ice. 8. The Lava Beds of California and Idaho, and their Relation to the Antiquity of Man. By Professor G. FREDERICK WRIGHT, LL.D., F.G.S.A., Oberlin, Ohio, U.S.A. A brief account was given of the extent of the basaltic beds on the Pacific Coast, and evidence was presented in proof that they were in the main of posttertiary age. New evidence, collected by Professor Wright and by Mr. Geo. F. Becker, was presented confirmatory of the genuineness of the Calaveras skull and other human remains reported upon by Professor Whitney as from under the lava flow of Table Mountain, near Sonora, California. Evidence was also presented of the discovery of a small clay image under the western edge of the lava plains of Idaho, at Nampa. These lava outbursts are correlated with the Glacial period in the eastern part of the continent. 9. Report of the Committee on Excavations at Oldbury Hill. 10. Preliminary Notes on the Excavations at Oldbury Hill. No rock-shelters like those in Central France have yet been discovered in this country. In France they occur in a cretaceous district, where the strata weather unequally, so that projecting ledges of rock are left over recesses worn out by natural agencies, and adapted by paleolithic man for his rude dwelling-places. Large numbers of flint and other implements, mixed with the débris of animals on which he fed, afford proofs of his habitation. Sites presenting somewhat similar adaptabilities occur on Oldbury Hill, near Ightham, in Kent. This hill rises above the level of the surrounding Lower Greensand to the height of 600 feet, and is capped by some of the hard siliceous grits of the Folkestone beds, which form a flat top to it, 137 acres in extent. Its isolation and commanding position caused it to be chosen for the site of an encampment, first by the Britons and subsequently by the Romans. For the same reasons, it had attracted at an earlier date palæolithic man to the district, and he left a considerable number of his flint implements scattered around and on the slopes of the hill. This led Mr. Harrison and myself to suppose that the capping of rock, which was underlaid by loose friable sands, and overhung in places, might have afforded facilities for rock shelters; and for the purpose of inquiry Mr. Harrison undertook to direct the necessary search, aided by a grant from the British Association. The summit of the hill and much of the slopes are, however, so thickly wooded that it was with difficulty that a proper site could be fixed upon. The one that seemed to us and others most likely was on the north-east side of the hill, where a large mass of rock formed a low cliff with a small cavity beneath it. Excavations were accordingly commenced here, but the fallen blocks and the large roots of the adjacent trees so interfered with the work that, after digging to the depth of 2 to 3 feet without making any discovery, the spot had to be abandoned. It next occurred to Mr. Harrison that the talus, which extended for some distance on the slope in front of this ledge of rocks, might have carried with it some of the inhabited ground, or might have covered some of the original sites. He therefore proceeded to dig lower down the hill where the ground was undisturbed and free from large trees. Here he was successful in finding, at a depth of about 3 feet, a considerable number of flint implements and a large quantity of chips and flakes, which look as though the implements had been made on the spot. There is little to distinguish these implements from the ordinary valleyimplements that are so common in the Ightham district, except that, on the whole, they are more carefully finished and of fewer forms. The prevailing forms at Oldbury are the small pointed lance-shaped implements worked on both sides, and the thin, neatly-worked, long, triangular, spear-shaped, of which there are some highly finished specimens. These are forms which occur at Le Moustier, as do likewise some of the ruder Oldbury forms. As also at Le Moustier, there is an absence so far of bone implements, so common in the other Dordogne shelters. Again, at Oldbury the more ordinary valley-types are wanting; and so also are rolled and worn specimens so frequent in other localities. The explorations, however, have been at present on too limited a scale to allow of any general conclusions being drawn. But as there are still other spots at Oldbury which are likely to have been used for rock-shelters, it is to be hoped that the work may be continued, and further information obtained. Mr. Harrison's Report, which gives the result of the work up to the present time, is both satisfactory and encouraging. 11. Report of the Committee on Elbolton Cave, near Skipton. TUESDAY, AUGUST 25. The following Papers and Report were read : 1. On the Occurrence of Pachytheca and a Species of Nematophycus in the Silurian Beds at Tymawr Quarry, Rumney. By J. STORRIE. For a long number of years I have been interested in the fossils known by these names, and for that purpose have collected and sectioned wherever practical all specimens likely to show structure, and the collection now submitted are the results. In the Silurian beds exposed near Cardiff, which are over 900 feet in thickness, I have found Pachytheca in nearly every individual bed, from the very top of the Ludlow to the bottom of the Wenlock series, and although Nematophycus has not occurred in so many beds or has escaped my notice, it has exactly the same range, as I have found it in the top of the Ludlow and at the base of the Wenlock and in a considerable number of intermediate beds; still it is only in two beds in Tymawr Quarry that I have found the two species in question preserved in a state which allowed of transparent sections being made. The lowest bed is a muddy sandstone, full of Rhynchonella Stricklandi, and the other being a thin parting on the top of the Ctenodonta sandstone of Sollas, and about 10 feet above the Rumney grit. The specimens from the last bed being much superior to the lower one, I will only deal with it. This bed is only from 1 to 2 inches in thickness, and contains large numbers of Discina_rugata, of Lingula two species and a large Orbicula with casts of branching Zoophytes of a species not known to me; it is wholly of a marine character, and at a point west-south-west becomes of a concretionary character, every little nodule of which when broken open shows a fragment, or a whole, Lingula, Discina, Conularia, or other shell; the whole bed is highly impregnated with iron, which rapidly oxidises when broken and exposed to the atmosphere, and the difficulty is to understand how perhaps the most mineralised bed of the section should contain the best preserved specimens of these organisms. When preserved in mudstone the Pachytheca and Nematophycus do not display any minute structure, the form and general appearance being the only points to be recognised. When preserved in limestone the carbonaceous character is most readily noticed, but the microscopic details are not very perfect; its resemblance to fragments of drift-wood is very striking to the naked eye or when a hand lens is used. When preserved in concretionary nodules the outer wall is usually perfect, but the cellular structure of the interior is reduced to a pocket of carbonate of lime or oxide of iron. There are undoubtedly two totally distinct organisms known at present as Pachytheca sphærica; one of which is a perfectly spherical body, variable in size like the Pachytheca and like it consisting of a more compact outer layer and a less dense centre, but, however thin this is cut, it never contains any internal structure, showing only a chitinous-like appearance, with sometimes a fungous-like growth on the exterior; this, I think, is no doubt the egg of a crustacean, more especially as Pterogotus has been found in this quarry and in a section of the same beds. Yesterday, a member picked up a specimen which may likely turn out to be a fragment of Slimonia. Pachytheca may be described as a thick - walled globular rind of tubular tissue, with small intertubular spaces enclosing a small cavity of much looser and more branched tissue, coral-like in appearance, which is in continuous structural connection with the radiating thick-walled, slightly branched and rather densely packed tubes of the exterior, the intertubular spaces in the exterior portion, as seen in transverse section, being small in comparison with the intertubular spaces found in Nematophycus. I have examined large numbers of Pachytheca to see whether any hilum or point of attachment was present, and have never seen any indication either on the external wall or in the internal structure of any such as might be reasonably expected to show some differentiation, were there any ground for believing that it was either a fruit of a conifer, or the conceptacle or even one of the floats of a seaweed like sargassum or fucus. Nematophycus occurs principally in small fragments, waterworn and irregular in shape and never over an inch in length, and in only one specimen have I found any appearance of branching; in this case it was a small stem from the Discina bed about 4-inch in diameter, rather oval in section and with one branch of barely 4-inch diameter and a 4-inch long, which was again forked at the extremity, the branchlets being about-inch in length and nearly the same in thickness. The tissue of the outer part of the stem was slightly differentiated from the interior, but essentially the structure was the same, and the apparent difference may have been more dependent on the different degree of oxidisation of the iron in the weathering of the fossil than any bark-like difference of structure. |