BIELBECKS. 149 
The shells are all white, never compressed, not particularly tender, 
and very entire. The black marl which contains them is not laminated, 
nor are the shells arranged in it in any peculiar order or position, but lay 
mixed with bones from top to bottom indifferently. It was doubtless 
deposited beneath the waters of a marshy pool, which nourished the 
planorbes, limne®, &c., and received by some little streamlet, or occasional 
inundations, the helices from the land, and succineae from the adjoining 
plants. The elephant, rhinoceros, and other animals died near the lake or 
the stream, and their partly disintegrated remains were washed by the 
same forces into the same repository, or brought thither at a later 
period, along with abundance of marl and gravel attesting the operation 
of a powerful and considerable current of water. By these latter accu- 
mulations the lake was filled to the level of the surrounding surface. 
In this lacustrine deposit of the elephantoidal or antediluvial ®ra, are 
observed facts of great value towards elucidating some material points 
regarding the early condition of Yorkshire. 
First— Since all or nearly all the mass of clay and marl, and chalk and 
flint gravel, may be reasonably admitted to have been brought from the 
neighbouring low ranges of lias, and the surface of the wolds, there is 
nothin o' to indicate the operation of floods of extraordinary power or 
extent,° except the presence of some pebbles of limestone and sandstone 
derived from the western hills, which lie in the upper parts of the 
deposit. These are few in number compared to the mass of flint and 
chalk gravel, and, though requiring the admission of the flowing of 
antediluvial rivers or other currents from the west, do not demand for 
the explanation of their accumulation here, more than the action of such 
limited floods or inundations as might deposit the rest of the gravel. 
Such inundations were frequent before the deposition of the ossiferous 
marl, and were repeated at a later period ; and it appears to be proved 
both by comparison with the analogous deposits at Hessle and Bridling- 
ton and by the superposition of the ordinary diluvium in the south- 
eastern part of the vale of York, that the latest of these inundations was 
anterior to the movement of waters which brought many Cumbrian rocks 
