Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/483

 water of the river Deben, which can vary but little from that of the sea on the adjacent coast, from which this part of the river is only five miles distant. The upper cliff (o', fig. 21), which is not well exposed, is about 12 feet high, and must formerly have been higher, as blocks of the consolidated bed of Bryozoa capping the hill higher up are found at its base. They may have toppled over the brow of the old cliff, or been detached and carried a short distance by ice-action. At all events it is evident, from the way in which the blocks of Coralline Crag, 1, 2 in fig. 22, have impressed and squeezed up the lower layers of Red Crag in which they rest, that they fell on the spot where they now lie whilst the Red Crag was in course of formation, and that the upper part of the Red Crag was deposited subsequently to the fall of the blocks. The larger of these angular blocks of Coralline Crag may weigh more than a ton. In addition to these large blocks there are many smaller ones — some perforated by Annelids, and others covered with Balani (B. crenatus). Together with these are a number of pebbles of flint, some coprolites, and some large masses of angular and unworn flints. Interspersed with this coarse shingle are an abundance of shells (chiefly Mytilus edulis) with both valves. The Pholas- perforations commence at the top of the upper shore, and pass over the brow of the lower cliff, o. A few feet back from the face of the section the Coralline Crag rises to the surface of the ground.

To ascertain the position of the lower shore-line, I had a trench dug at the bottom of the pit and below the level of the upper shore, s' (fig. 21). I found the Red Crag to extend about 4 feet deeper, and at its base a shingle composed of phosphatic nodules and of large flints, over which there was a thin bed of Mytilus edulis, almost all with the two valves, and apparently in the spot where they lived. This shore-line is 22 feet above high- water mark. Its character is better seen in a pit (G) situated on the other side of the old reef, 350 yards west of the pit D (see Pl. VI.). The details of this pit are given in fig. 23. On the upper shore in pit D I found only two large blocks of Coralline Crag ; but on this lower shore the blocks were many, whilst numerous smaller fragments were dispersed throughout the section, showing the removal of the adjacent Coralline Crag to have been more active at the commencement of than further on in the Red Crag period. Flints and phosphatic nodules are dispersed here and there. Apparently this pit is at a rather greater distance than pit D from the old submerged reef.

The occurrence of these transported blocks of Coralline Crag is peculiar to these pits. There are, however, few other pits so near as these to the Coralline Crag ; and the upper bed of the Coralline Crag is here also more compact than elsewhere. But although the debris of the Coralline Crag is nowhere else so abundant, it may nevertheless be detected in most of the pits of the Red Crag in this district. Small pieces and fragments of the harder seams of the Coralline Crag, together with its Corals and Bryozoa, are extremely common in the Red Crag at Waldringfield, one mile direct from Sutton. I have also found worn fragments of the Coralline Crag in the Red Crag at

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