Downloaded from http://pygs.lyellcollection.org/ at University of Saskatchewan on March 17, 2015 KAIKLEY : BLOWING WELLS. 421 attention has been drawn to them, In this paper it is shown—That these currents vary in nature and amount with the changes of the barometer just as the volume of the air in any closed receiver varies strictly with the atmospheric pressure when the influence of temperature has been eliminated. Hence the observations may be considered to prove the existence of large cavities or series of cavities or fissures in the underlying strata adjacent to the wells. In the case of the well at Solberge, this cavity has a capacity approximating to ten millions of cubic feet. A chamber 217 feet each way—length, width, and height, would have nearly the same capacity. GLACIAL SECTIONS AT YOEK, AND THEIR RELATION TO LATER DEPOSITS. BY J. EDMUND CLARK, B.A., B.SC, ETC. THE various deposits of boulder-clay, sands, gravels, brick-earths, warp and peat, near York, have been sufficiently exposed by build• ing operations, brick fields, and gravel pits to show this very simple relation. Resting upon the deep-seated Triassic rocks lies the irregular boulder-clay, which forms all the higher ground, reaching in Severn's Mount to 100 feet above the river Ouse. Where the stream escapes from between its undulations, the top• most laj^ers have been washed and re-arranged as glacial gravels. Its hollows have been levelled up with the sediment thus pro• duced, forming the brick-earths and warpy clays; whilst peat deposits have completed the work where the depth, elevation, or remoteness of the original hollow prevented the brick-earths from accomplishing that end. An examination of Plate XXIII., Fig. 1, wall show the fol• lowing relations. The glacial beds form the chief feature of the region, not only monopolising all the ground more than about 30 feet above Downloaded from http://pygs.lyellcollection.org/ at University of Saskatchewan on March 17, 2015 422 CLARK 1 GLACIAL SECTIONS. the Ouse level (or 50 to 60 feet above that of the sea), but also forming extensive low-lands, except close by the river. Where these are sandy, and rest on clay, healthy commons still reznain, such as Tilmire, Langwith, Strensall, and Riccall. At present, unfortunately, there are no good sections in the glacial beds, but their character can be made out near the New Goods Station, at several points round the Mount, especially on Holgate Hill, and also at the Poppleton junction of the Harrogate and North lines, about two miles out. But, before discussing former exposures, it will be best briefly to indicate how the latter deposits are related to the boulder clay. The chief gravel beds lie on either side of the Ouse, below the city. Brick-clays are worked by (1) a low, marshy spot called the Foss Islands ; (2) west of Heworth road; (3) near the Poppleton Junction; and (4) on the S.E. edge of the large basin- shaped area called Hob-moor. The race course, Knavesmire, lying between the two glacial ridges separating Hob-moor from the Ouse, is also a brick-earth. Peat deposits cover a large area at Askham bog and help to fill various small, elevated depressions, such as Campleshon pond D, on the Bishopthorpe Road, part of St. Paul's Square C, and a patch in Mr. James Backhouse's nursery gardens E; overlooking Eob-moor below Severn's Mount. The last two are concealed by Alluvial Deposits, which are about two feet thick at the nurseries. Yet here, at the peat surface when a fresh face i? exposed, plants of the Water Violet, Hottonia palustris, not unfrequeutly spring up. The seed must have laid dormant for ages apparently, for not only is there no spot at hand whence it should come, but the position in its present state is too dry for favourable development. Bones of deer and fragments of a hollowed oak (perhaps a coffin or canoe) have been dug out from here. A canoe is possible, as there are indications that all Hob-moor may have formed a lake at one time. Such, certainly, was the part called Askham Bog at the opposite (S.) end, covering an area of 1.1 miles by \ to \ Downloaded from http://pygs.lyellcollection.org/ at University of Saskatchewan on March 17, 2015 CLAKJ£ : GLACIAL SECTIONS. 423 mile wide. The peat reaches a depth of 8 feet, and in wet weather the whole area is under water. The glacial ridge to the S.S.E. rises steeply above it, and must sink as steeply underneath. Probably the depth of the hollow, as well as its distance from the river, prevented the brick-earths from filling it up. Two or three patches of peat also occur at the river level, perhaps indicating* previous channels, like the bayons of the Mississippi. Both upon Clifton Ings and below Clementhorpe it is interesting to note that the river meadows sink away from the river, so that they are drained by small sluggish becks running parallel to the main stream. Another patch lies close by Ouse Bridge, under Brett's Brewery, the managers of which I have to thank for the following section obtained in their well:— Feet. Inches. 1. Soft warp, with, sand 27 0 2. Blue clay, (perhaps like the local brick clays) 10 0 3. Fine sand 12 0 4. Soft bog, and stone boulders ... 5 0 5. Dark yellow soft clay 6 0 6. Very loose gravel and pebbles, with water ... 2 0 7- Very fine sand ... 10 0 8 &9. Not given •> ' 10. Soft brown free stone ... 12 6 11. Very soft and open gravel bed 3 6 12. Sample (sic), blue free stone ... 7 0 Oi Hi 1 13. Soft blue and yellow clay, mixed 2 11 14. Brown free stone 5 10 15. Rock blue stone and soft sand 17 0 o u FM 16. Brown iron stone, left off in stone ... 19 0 Total (alluvial and glacial, perhaps 72 feet) . 139 9 The River and Brick-earth beds, very remarkably, lie under 40 feet of sand and clay deposits, and have been regarded as inter-glacial, but I have not seen any adequate proof for such an inference. That the river deposits are in many parts very deep was well shown by the nine borings and excavations when the Downloaded from http://pygs.lyellcollection.org/ at University of Saskatchewan on March 17, 2015 424 CLARK. : GLACIAL SECTIONS. new engine-house was erected at the Water Works. Warpy clays were first met, the dark clay being separated by sand so mi• caceous that it shone like silver; then came a dark clay full of plant roots to a depth of 20 feet, whilst even to 50 feet there was nothing of distinctly glacial origin. One of the borings, beginning 20 feet above the river's summer level, gave as follows:— Feet. Clay, of various qualities, but always 2 feet of blue at the base ... ... ... ... ... 22 Sand (varying up to 15| feet at one boring) ... 8 Clay, free of stone... ... ... ... ... 20 Sand ... ... ... ... ... ... ••• 11 Loamy clay... ... ... ... ... .. 2 Total ... 63 This great depth of apparently fluviatile deposit is strik• ing from the close proximity of true boulder clays, which rise to the surface about 80 yards off. At this point it will be noticed the Ouse bends sharply where, comparing York mole-mills to mountains, it meets the outlying spur of Severn's mount, cut by the river at Clifton Scope. A quarter of a mile to the north, at the Harrogate Junction, the railway enters a cutting 15 to 20 feet deep, where the glacial beds are still fairly exposed. They are sandy and gravelly, large boulders are scarce, but ice-scratched pebbles abound. The junction of the brick-clays with these beds occurs a yard or two S. of the signal box. It is, however, exceedingly obscure, even when best exposed. Just N. of the box the brick-clays rest on the sandy g-lacial beds, which are semistratified, dipping 1 in 8 or- 9 to the S. Between the Harrogate and North line a large space has been cleared, leaving at the end a slope 200 feet long and 20 feet high, facing south. The east part had the same semi- stratified sandy clays—rearranged glacial beds—in which, at this point, no scratched pebbles were found. An irregular, nearly Downloaded from http://pygs.lyellcollection.org/ at University of Saskatchewan on March 17, 2015 Fig. 4, Downloaded from http://pygs.lyellcollection.org/ at University of Saskatchewan on March 17, 2015 CLARK : GLACIAL SECTIONS. 425 vertical, line separated this from beds of boulder clay, not so sandy and full of ice-scratched pebbles but containing' some boulders. The new Foss Islands branch of the N.E.R. exposed some interesting sections; and here, best of anywhere, was seen the junction of brick-earths and glacial beds. The Foss Islands are a marshy spot, where the stream of that name receives the Tang Hall Beck. So inaccessible was the city at this point that no artificial defence was ever erected. The peat and clay, where their surface is lowest, are 9 to 12 feet deep, resting on sands and gravels, probably glacial. These must be about 5 feet below the present Ouse level, or not 20 feet above the sea. The brick-clays, however, rise considerably at the sides of the beck, bnng 30 or 35 feet thick where worked on the south (Walmgate) side. Here they rise about 20 feet above the Marsh, as well as on the north (Laperthorp) side, (Plate XXIII., Fig.