ROCKS OF SCOTLAND. 339 
land, in a deposit at least as old as these shales; whereas the 
system in Scotland has hitherto failed to yield any trace of the 
vertebrata. But though not yet prepared to demonstrate that 
fishes swam in this corner of the ancient Scoto-Silurian ocean 
over the argillaceous shales, these must have been traversed by 
many a restless mollusc and crustacean, — the one-chambered 
bellerophon, and the many-chambered orthoceratites, — by 
Calymene, Cheirurus, and Phacops, with their nicely-adjusted 
armor of many joints, and by the massive Ilenus, with its 
double buckler. With this upper formation of the Lower Silu- 
rian division, deposition in the earlier Palzozoic period seems 
to have ceased in this district. Farther to the south, however, 
on the shores of the Solway, the shales, in a somewhat altered 
form, pass into the lower beds of the Upper Silurian, and ex- 
hibit some of its characteristic fossils. And with these the Old 
Grauwacke record, as a record of life and death, abruptly closes 
in Scotland, and a chapter of purely physical revolution begins, 
—a chapter perplexed by passages of doubtful meaning, and 
by many different readings, but which tells, in every page, of 
widely-extended convulsion and upheaval, and of the operations 
of deeply-seated forces of a power incalculably great. 
During the ages of either the Upper Silurian or the inferior 
Old Red Sandstone, the deposits of the Lower Grauwacke 
division in Scotland seem to have been the subject of enormous 
lateral pressure, which raised their strata into many folds and 
ridges over wide districts, and, as there is reason to believe, 
elevated them above the sea level. Sir Roderick Murchison 
reckoned in the neighborhood of Girvan from five to six axial 
lines in a section of less than eight miles; and on the east 
coast, in the instances made so famous by Sir James Hall, axial 
lines are, as I have already had occasion to state, still more 
numerous. Nay, the great difficulty which lies in the way of 
determining the true place of the older rocks of our southern 
