POST-TERTIARY FOSSILIFEROUS DEPOSITS. 



27 



Cyprina islandica, and near the bottom of the section. This is pre-eminently the case in 

 a clay pit west of Paisley, and at Jordan Hill, about three miles north-west of Glasgow, 

 where it is found fourteen feet below the surface. 



The position of the fossils in the clay is not precisely the same in all the glacial beds 

 of the same geological horizon. 



When the Greenock New Docks were excavated the laminated clay was cut through 

 for many feet, until the imstratified Boulder Clay was reached ; and the junction was 

 sharply marked by a thin layer of whitish-coloured clay, three or four inches thick, 

 containing Foraminifera and Ostracoda. This thin stratum of whitish clay was followed 

 by a darker coloured clay crowded with Mollusca, amongst which were Cyprina Islandica, 

 Fecien Islandicus, and Tellina calcarea. 



At Kilchattan tile-works, Buteshire, the fossils of all species are most plentiful, above 

 the laminated clay, in a bed of sand or gravelly sand, which lies between the clays and 

 the upper gravel. 



At Elie, Fifesliire, the fossils are plentiful near the top of the clay a little under the 

 gravel, and amongst them are Leda ardica and Thracia myopsis, with Ostracoda of an 

 extremely arctic character. 



In many other deposits of the same age an odd shell is only seen occasionally. This 

 not unfrequently happens at different points of the Paisley beds. In a brickfield on the 

 west side of the Cart, near the park, one or two specimens only by diligent search may 

 be met with, although they are plentiful in cuttings close to the spot. 



Before a microscopic examination of the clays was made the fossiliferous beds under 

 discussion were described as situated between an unfossiliferous upper clay and an 

 equally unfossiliferous laminated clay. It will be seen from the foregoing observations, 

 however, that they occupy no such position. Foraminifera and Ostracoda of marine and 

 estuarine character occur in the laminated clay, where the Mollusca are either absent or 

 rare, and continue throughout the upper clay, where the Mollusca gradually disappear. 



It thus appears possible to trace by these fossiliferous beds, occurring in the valley 

 of the Clyde, (1) the pouring down of the muddy waters of an arctic river, (2) the 

 subsidence of the land to a depth sufficient for the abode of an arctic fauna in the waters, 

 (3) the gradual disappearance of the marine fauna owing to the re-elevation of the 

 land, (4) the recurring of a river, with far broader boundaries than now exist. 



The height above the sea of the arctic-shell-clays around Paisley (including the 

 bed on the higher ground, covered with Boulder Clay, which has been previously 

 described) is from twenty feet to sixty-four feet. 



The following Ostracoda have been found : 



Aryillcecia cylindrica, G. 0. Sars. 

 Potitocypris viytiloides (Norman). 



