228 The American Geologist. April, 189 
This rock makes a sharp change in the topography wherever it 
appears above the surface. It does not disintegrate easily, and 
hence usually makes an abrupt cliff, while its great boulders are 
scattered far down below its present outcrop. 
Under this hard sandstone, we find about 30 ft. of sandy shales 
filled with plant fossils. Then one foot of hard, black slate caps 
one foot to one and a half feet of coal. This coal is often worked 
and is of good quality. 
About 10 feet of shales underlie this coal, which brings us down. 
to the main mass of the Great Congiomerate. 
W. Va. University, Dec. 12th, 1891. 
THE TIN ISLANDS OF THE NORTHWEST. 
E. W. Ciaypore, Akron, O. 
if 
The Cassiterides or Tin islands of the ancients were the granitic 
masses of Cornwall and the Scilly islands. Hither came in days 
before the dawn of written history (except perhaps Egyptian) 
the enterprising mariners of Tyre, to buy from the Britons their 
much prized and very scarce metal. By craft and daring in nav- 
igation, they for many years kept the destination of their tin- 
ships a profound trade secret. Few dared follow them out be- 
tween the pillars of Hercules into the foggy and stormy Atlantic, 
and Pheenicia was consequently for ages the central mart for the 
sale of this metal—the stannary of the world. 
Not, however, for the sake of tin pure and simple, did these 
old Pheenician mariners undertake the voyage from the Levant to 
St. Michael’s Mount and back-—6,000 miles of sea, and often out 
of sight of land. Tin alone (the p/liambum album or white lead 
of the Romans) was of little use. Pliny,* it is true, speaks of 
tinning copper vessels, but Pliny lived at a comparatively late 
date. It was the peculiar and intense hardness that characterizes 
its alloy with copper that gave this metal its value among the 
ancients. Bronze was the material of which all metallic cutting 
tools were made before the discovery of steel, and for many years . 
afterwards until this latter became cheap and easily wrought. 
It is therefore needless to point out the great advantage possessed 
by the nation that held the secret of the Cornish tin. Others 
*“Staunum illitum aeneis vasis compescit aeruginis virus.” Plin. 34, 48, 
