99 
generall}^ found covering the grit rocks in this neighbour- 
hood. The drift remains found in the valley, as we have 
seen from the sections already given, consist of well- 
rounded stones, many of them being syenite from Ennerdale, 
and the greenstone found in situ in the Lake district is not 
uncommon. 
Accepting the theory of the subsidence of the land to the 
extent of several hundred feet after the existence of th.e great 
glaciers, the whole of the vale of York and the surrounding 
districts, including the valley of the Calder, would be 
submerged beneath the water. The boulders would be washec 
from the clay imbedding them and subjected to the attrition, 
of the waves; the scratches would, in course of time, be 
obKterated ; all the sharp angles worn away ; and, it will be 
easily imagined, how the water-washed boulders may have 
been re-deposited in their present localities, filling up the 
deep-sheltered valleys, and forming the level surfaces so often 
met with in Calder vale. The stratified appearance presented 
by the deposit, where a section can be seen, and the thin beds 
of sand interpolated amongst the layers of boulders, suggest 
very strongly an estuarine deposit subject to the tidal action of 
the waves. The presence of the trunks of large trees support 
this theory. Many of them are probably deposited near the 
situation they occupied whilst living; instances having been 
found where the roots and part of the stems are still imbedded 
in the soil in which they grew prior to the submergence of 
the land. The only serious objection to this theory is the 
absence of any remains of mollusca or other forms of animal 
life, none having hitherto been discovered. This difficulty, 
however, is no greater in the case of an estuarine deposit than 
it would be on the supposition that the boulders were brought 
down by a river or accumulated in a series of lakes. The 
discovery of any shells would tend, in a great measure to the 
solution of the question. 
