206 Mr. R. Walker on Clays, containing Fossils, 



marsh- and perhaps other plants had grown and decayed (how 

 long, it would be impossible to conjecture) before the land again 

 began to sink under the sea; during which time the deposit 

 would be exposed to the tear and wear of the waves, when doubt- 

 less many of the organisms, together with a great portion of the 

 bed itself, would be washed away. It would be difficult to ascer- 

 tain, from the manner in which the third and second beds seem 

 to have been deposited, to what extent the land subsided at the 

 time, and whether the subsidence was gradual or rapid. The 

 continuation of the latter of these beds has been noticed at 

 other places in the neighbourhood, at greater elevations. For 

 instance, in a cutting to divert a small stream on the farm of 

 St. Nicholas, about half a mile south of the clay, this littoral 

 deposit was passed through : here it is from 12 to 15 inches in 

 thickness; and the composition and contained fossils are iden- 

 tical with the second bed of the section. At this part the de- 

 posit is laid upon a gentle declivity arching round to the 

 Kinness valley, and from 27 to 30 feet above the sea, thus 

 occupying an intermediate position between Dr. Chambers's 

 64-feet beach at this place and the sea-level ; he states, however, 

 that here " the sea has made several shifts of level without in- 

 denting the land''*. This stratum was likewise exposed, on the 

 north side of the Kinness valley, about three years since, while 

 altering a wall at the gas-works, at an elevation of 35 feet above 

 the sea, the ground sloping towards the south. This bed was 

 again laid open by the present drainage-excavations ; but this 

 time it was on the west side of St. Andrews, at the height of 

 21 feet above the sea, and contained all the littoral shells enu- 

 merated in our second bed. 



Besides the preceding, there is additional evidence, though of 

 a different kind, of the sea having stood at a higher level than 

 at present, in recent times, geologically speaking. This is fur- 

 nished by an isolated patch of sandstone that crops out at the 

 south end of the " west sands " being quite full of the holes of 

 Pholas crisjmta. This rock is within a foot or two of high-water 

 mark, and about 14 feet above the habitat of the Pholas at the 

 present day, which generally lives between 2 to 3 feet above low- 

 water mark and a few fathoms beyond. They do not appear 

 from choice to make their habitations in sandstone, but rather 

 prefer shale or limestone, if these rocks can be had at suitable 

 depths. From the numerous borings in the sandstone in ques- 

 tion, it would seem that it had continued for a long time at a 

 depth in the water favourable to the organization of these mol- 

 lusks ; and as the land was gradually elevated, they appear, from 

 their holes still visible here and there in the intervening rocks, 

 * Ancient Sea Margins. 



