98 Report on the Coal said to have been found 
deep and extensive lake; to which supposition the subse- 
quent deposit of repeated layers of a highly combustible 
schist of undoubted vegetable origin lends great probability. 
But, having mentioned the evidences for such a period of 
repose, the turbulent state of things which followed must be 
noticed. The immense masses of siliceous and siliceo-ferru- 
ginous conglomerate which overlie these clayey strata, and 
overspread the country far to the east and southward, must 
have been swept down from a higher level,—either from the 
rupture of the boundaries of large inland waters pent up at 
higher levels, and liberated by some disruptive action within 
the crust of the earth, or from a temporary submergence of 
the dry land, or a great portion of it under the sea, sub- 
jecting the surface to powerful and irregular currents in a 
shallow ocean kept unusually turbulent, probably by repeated 
elevation and depression of the land at short intervals. I 
have mentioned that the casts of marine shells occur occa- 
sionally, imbedded in the substance of the conglomerate. 
An extended and close examination of these beds, and the 
formations with which they are associated, and a careful com- 
parison of their fossil contents, will be required thoroughly 
to establish their ages in relation to each other, and to 
geological changes and epochs generally. 
The coast from the mouth of the “ Mersey’ to the 
mouth of the “ Rubicon,” (Port Sorell), is comparatively 
flat, presenting seaward a line of sand-banks, more or less 
elevated and rounded, with broad beaches, broken only at 
long intervals with projecting points of basalt, which, with 
the exception of the Bluff Head, running out on the western 
side of the entrance to Port Sorell, are low and acuminated, 
“affording no shelter anywhere, and scarcely sufficient as 
a bulwark to defend the land from the lowering and 
encroaching influence of the sea. 
