| T. Mellard Reade—On the Lower Trias. 555 
If, as I have reason to believe, the Triassic deposits of the North- 
west of [ngland as they now exist fill up the sites of pre-Triassic 
basins and valleys, the absence of underlying Permian rocks over a 
large area surrounding Liverpool is a remarkable fact. The Bunter 
Sandstone was proved to be at least 1200 feet thick in the Bootle 
boring, and the additional 200 feet of sandstones and marls below 
that depth did not present any decided Permian characteristics. 
They became gradually more calcareous and of a deeper purple colour. 
It is on the margin of the Triassic deposits that the undoubted 
Permians occur, and these facts would seem to point towards an 
unconformity between the Trias and the Permian. If this be a 
legitimate deduction, the Permian rocks must have been largely 
removed by denudation from these valleys before the Trias was 
_ laid down. 
Whence then came the physical change which turned the valleys 
into areas of deposit? If they were filled up in the way the sub- 
aerial delta theory requires, we shall have to postulate the existence 
of very high land, probably of a granitic nature, for a river could 
not pile up a homogeneous delta of sand and pebbles from 1200 to 
2000 feet thick without having a considerable gradient. If then 
such a plateau or Alpine range then existed, what has become of it? 
Why should it have been destroyed, when a lesser orographic 
feature like the Pennine Chain remains ? 
If, however, we look upon the areas in Lancashire and Cheshire 
occupied by the Triassic rocks as subsided valleys forming arms of 
the sea in Triassic times, and we can show with a reasonable degree 
of probability that sandstones having the characteristics of the 
Bunter could be laid down under such conditions, we shall have 
advanced a considerable step towards a solution of the problem. 
I have shown that tidal action affects the bottom of the sea to the 
profoundest depths,’ and is especially effective in embayments and 
straits. The Trias of Cheshire and partly that of Lancashire lies 
in an embayment between the Carboniferous mountains of Wales 
and the Carboniferous hills of Lancashire and Cheshire, and this is 
connected with the Birmingham Triassic Basin and the strait-like 
neck of Trias at Bridgenorth. 
Indeed, if a subsidence of England and Wales were to take place 
now to the extent of 400 feet, most of the Triassic deposits would be 
submerged, and the embayment, though more extensive, would ap- 
parently follow or be concentric with the Triassic boundaries. This 
has long appeared to me a remarkable fact, and a strong testimony 
of the permanence of certain orographic features of the earth’s sur- 
face. In this connection we must not lose sight of the possibility 
of a great extension of the Triassic Sandstones existing under the 
bed of the Irish Sea. Of this there is the strongest probability 
from the known existence of bordering deposits of Trias on the 
coasts of England, Scotland, and Ireland, sending offshoots up the 
valleys in the way already described. 
1 Tidal Action as a Geological Cause, Proceed. of L’pool. Geol. Soc. 1873-4 ; Tidal 
Action as an Agent of Geological Change, Phil. Mag. May, 1888. 
