484 S. V. WOOD, JTJN., OIT THE NEWEB 



produced from denudation of the beds of Stage II. by the sea as the 

 land rose, such as are seen in fig. I. ; and as by emergence this 

 gravel reached the surface, it was in many parts destroyed by the 

 waves while still accumulating in the parts submerged ; but where 

 it was overspread by the moraine of the ice as this advanced upon 

 it, while still beneath the sea, in the way presently to be described, 

 it was more generally preserved, though afterwards to a certain 

 extent destroyed by the thickening or shrinking of the ice. 



In places in Sheets 66, 67, 50, and 47, a band of moUuscan 

 remains, more or less fragmentary and worn, occurs in this sand 

 and gravel immediately below its junction with the Chalky Clay, 

 as shown by ^ in fig. XIII. The species identified from this 

 band (principally from Hopton, the place whence that figure is 

 taken) are given in the column of the list in my father's first 

 Supplement to the ' Crag MoUusca,' headed " Middle Glacial." 

 These remains present much the same aspect as those from the 

 newer part of the Red Crag ; but there are some of which no trace 

 has been found in the Crag, such as Tellina baltJiica and Venus 

 fluctuosa, both of which occur in the Bridlington bed, and another, 

 unknown elsewhere, to which my father gave the name of Trophon 

 mediglacialis, all of which are not uncommon in this band. There 

 are others, such as Venus fasdata (which is unique in the Crag), 

 that occur in this band in great profusion ; and this is one of the 

 two species found in Sheet 47, the other being Astarte compressa, 

 also occurring in Sheet 67 in great profusion and in a more perfect 

 state than any other species than floaters, but which is also common 

 in the fluvio-marine Crag and in the sand b 1. There are also other 

 very small and tender species not known from the Eed Crag, but 

 which are Coralline-Crag shells, and have occurred in the Chilles- 

 ford bed and fluvio-marine Crag, and whose absence from the Red 

 may be attributed to the unfavourable conditions of that formation 

 for their preservation. In the " Introduction " above mentioned 

 Mr. Harmer and I gave our reasons, based on the character of the 

 species themselves, for regarding these remains in Sheet 67 as not 

 having been derived from the destruction of beds of Red or fluvio- 

 marine Crag age, or from the Chillesford bed ; but at the same 

 time we pointed out that the remains had an origin which was dis- 

 tant from the place of their occurrence, and had, most of them, been 

 greatly worn during their transport to it by currents along the 

 bottom, the larger shells being for the most part fragmentary, but 

 the smaller species and fry of the larger being often preserved 

 entire, though worn, while with these were an abundance of the 

 valves of Balanus, quite unworn, and of the papyraceous valves 

 of Anomia ephippium in a perfect state, but which the least 

 wear would destroy. The presence of these we attributed to their 

 having been adherent to floatiug bodies, such as seaweed, and 

 carried, thus adherent, floating in the currents which moved the 

 sand with the shells and shell fragments over the bottom, to 

 subside as they became detached ; all of which I still believe to be 

 correct inferences. 



