278 Messrs. Jackson and Alger on the 
exposed to the action of the waves, it becomes polished on the 
surface. This rock consists of thin folia of argillaceous slate, 
sometimes including a little mica, and is generally colored by ox- 
ide of iron. Comparatively remote from the trap, the shale 
assumes a grey, brown, or bluish-black color: more rarely it is 
spotted with green. 
Near Diligence River, the shale is almost black, and appears 
to be colored by carburet of iron. It here includes a large bed 
of compact limestone, a section of which has been formed by the 
encroachments of the waters of the Basin of Mines. A little be- 
yond Fox River, towards Cape D’Or, the sandstone, of a grey 
color, is seen to alternate with the strata of greyish-black shale, 
both of which are filled with relics of the vegetable kingdom of a 
former world. They are carbonized remains of various culmif- 
erous plants, which are converted into a compact bituminous 
lignite. Portions of ensiformleaves resembling those of the Iris, or 
blue-flag, were here observed, lying between, and included within, 
the strata of sandstone. 
The whole northern coast of the Basin of Mines, with the excep- 
tion of the’capes and islands of trap, before described, is composed 
of strata of sandstone and shale, alternating with each other, and 
presenting to the sea the edges of their strata, which are finely 
exhibited by this natural section. They do not attain a great 
elevation, rarely exceeding one hundred feet ; and where exposed 
to the waves, the strata have suffered much from their violence, 
and the shale is always worn away, exhibiting the bold ridges of 
sandstone strata, contrasted with the deep furrows occasioned by 
its decay. The strata of these rocks are from a foot to four feet 
in thickness, and are alternately stratified with each other in great 
regularity ; no limit being found to this alternation, we are unable 
