size in pl. II., fig. 8. The specimen agrees precisely in specific characters with the other teeth already known, and its rugose coronal surface is in a fine state of preservation. 1. EXPLANATION OF PLATES. PLATE I. Hybodus basanus, Egerton; portion of skeleton of trunk, lateral 1. Hybodus basanus, Egerton; portion of endoskeleton of trunk, lateral aspect, two-thirds natural size. Wealden; Sussex Coast. h.s. hæmal arches and spines; n.s. neural arches and spines; not. portion of notochord. [Brit. Mus. No. P. 6358.] 2. Synechodus (?) sp. dorsal fin-spine, natural size. Gault; Folkestone. [Brit. Mus. No. P. 6501.] 3. 4. 5. Synechodus illingworthi (Dixon); tooth, coronal (a) and inner Ditto; tooth, outer aspect, natural size Chalk; Southeram, Ditto; tooth, coronal (a) and inner (b) aspects, natural size. 6. Ditto; tooth, coronal (a) and outer (b) aspects, natural size. 8. Cestracion rugosus (Agassiz); tooth, coronal aspect, twice natural size. Lower Chalk; Warlingham, Croydon. [Brit. Mus. No. P. 6489.] EVIDENCE OF GLACIAL ACTION NEAR LEEDS. BY JAMES E. BEDFORD, F.G.S. The object of this paper on the above subject is to direct the attention of geologists and others to some good sections recently exposed to view in the Meanwood valley. For many years a quarry has been worked by Mr. B. Rowley in the ganister beds of the lower carboniferous shales and grits at Headingley, in the valley below Meanwood. This quarry is in rather an uncommon position for such excavations, in so much as it lies in the valley bottom and not on the hill side as is usual in quarrying in this district. The stone only becomes visible when the superincumbent material is removed by excavating. The rock appears to the eye to be fairly horizontal, but there is a dip to the S.E. which causes the rock to come to the surface within three or four hundred yards from the quarry. A thin bed of coal is seen to underlie the upper bed of ganister. Resting immediately on the rock is a bed of shale 8 feet thick, black and friable in its lower portions, but becoming yellow and softer in its upper beds. This shale is overlaid by a true glacial moraine composed of sandy clay with patches of sand, irregular in shape, and which occur in "pockets" in the clay. The sand in these patches is not bedded horizontally, but often inclined at a considerable angle. The moraine material contains great quantities of sub-angular blocks of grit rock of all sizes, from 2 feet 6 inches in diameter downwards. These grits are quite local, and consist almost entirely of ganister from the beds which the material now overlies. The glacial debris is evidently the work of a tongue of ice which stretched across the valley N.E. from the direction of Moortown. The bed of ganister comes to the surface and forms a low escarpment in that direction. It is quite evident that the ice crossed this escarpment and broke away masses of rock at this point, and carried them before it and under it to their present position. The escarpment is not more than three or four hundred yards from the quarry. The appearance of the blocks in the moraine leads me to believe this to have been the source of the blocks from the sub-angular form they still retain. I also infer that the weight of ice has not been very great otherwise the blocks would have been crushed to a greater extent and more sand produced. The moraine deposit has not been reassorted by the action of water; the blocks are rammed into the clay in all positions and at all levels; they also in many cases rest on their smaller ends. There is no appearance of bedding with the exception of the pockets of sand above referred to. No rocks from a distance have been found in the deposit excepting a small piece of chert which I found some years ago. Further evidence of ice movement appears from the condition of the shales below. These beds are contorted and crumpled in a surprising manner. In addition to the folding and squeezing of the shales, portions of the black or lower portion have been torn up and rammed into the clays above, fully five feet higher than their natural position. These blocks are seen to be bent and twisted by the pressure. The contortions only occur in the upper layers of the shale, the two feet lying immediately on the ganister being unaffected at this point shown in the sections; the six feet above, underlying the moraine, being much disturbed. The layers are seen to be crushed into sharp angular bends. There is no faulting of the bed rock or in the shales to account for the movement, and in my opinion nothing but ice could have produced the effect referred to. There is sufficient evidence for the assumption that the ice in its movement has not followed the direction of the valley itself, i.e., by the gorge in the Millstone grit at Meanwood Wood, for if it had done so we should certainly find large quantities of that material in the moraine torn away from the ridge formed by the fault which brings the grit to the surface at that point. The direction has been diagonally across the valley from the Plain of York. A glacier or ice sheet from the North Sea or from the Hambleton Hills would push local ice from the high ground about Moortown into the valley, although the main glacier itself may not have stretched so far at the time the deposit was found. The ice does not appear to have surmounted the escarpment of Woodhouse Ridge, where it may have had its direction turned down the valley; but there is no doubt that a tongue of ice passed round the N.W. of Headingley Hill from the direction of Meanwood Wood, as proved by a section exposed a few years ago near the Pumping Station at Headingley. This consisted of eight or nine feet of yellow sand and clay, full of rounded blocks of Millstone grit; this deposit is on the Elland flagstone or the shales immediately below it. Patches of clay overlie large areas in this district although the elevation is considerably above the levels of the neighbouring valleys. This clay may have resulted from glaciation, but it has been so much disturbed by roots of trees, when the great forest stretched over it, and by subsequent rain-wash, that little now remains on which to base any theories. A PERMIAN CONGLOMERATE BED AT MARKINGTON. BY REV. J. STANLEY TUTE, B.A. There is in the parish of Markington a small bed of Permian. Conglomerate, the existence of which seems to be worth recording. It consists of waterworn pebbles of Carboniferous Limestone and Sandstone, with angular fragments of Magnesian Limestone, embedded in a matrix of harder Magnesian Limestone. The thickness of this bed, where it is exposed, is about a yard, and its width a few yards, as far as it is traceable. The difficulty of tracing it further arises from its position. It occurs a little below the top of a steep bank about 50 feet in height, overgrown with a rather dense plantation, in which two out-crops appear. This conglomerate bed and another well-marked bed, upon which it lies, reaches to the bottom of the valley; and upon its eroded surface there runs the Markington Beck, a great part of which shortly disappears in swallow-holes and crevices of the Limestone. After passing underneath the hill, which is between Markington and Bishop Monkton, the stream bursts out in the latter parish. That this conglomerate bed once extended further to the west is clear from the occurrence there of boulders of this rock among the other boulders of the drift. There is clear evidence at hand that the loss by denudation has been very great, probably to the extent of 200 feet or more. The well-marked limestone I have mentioned is easily recognized amongst the other Permian beds, and consists of smoothed lumpy blocks of greyish-brown limestone, containing many sparry cavities, and probably represents the Lower Limestone of the county of Durham, the beds of which are described by Mr. Howse as "thin, hard, and knobby, and the entire thickness fissured and intersected with numerous perpendicular fissures or backs."* It occurs also half-a-mile to the east, near Wormald Green, in a very fine section 200 yards in extent, as a bottom bed; but I have failed to detect any traces of the conglomerate bed there. The section is * A guide to the collections of Local Fossils in the Museum, Newcastle. |