1T4 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



black shales of the Devonian. The Medina, the Clinton for- 

 mation, with its dycstone or fossiliferous iron ores, and the 

 Niagara and Lower Helderberg groups, were not deposited 

 over this island-area, and in approaching it thin out, as might 

 be expected. During the Medina and Clinton periods the land 

 extended far to the west, while during the Niagara and Lower 

 Helderberg times the extension was more or less easterly. 



THE CARBONIFEROUS ROCKS IN KENTUCKY. 



Shaler has considered the question whether the Appalachi- 

 an and Illinois coal-fields were at one time connected. Both 

 of these, as is well known, extend into Kentucky, of which 

 they occupy respectively the eastern and western portions, 

 and are separated by an interval of about seventy miles in 

 the centre of that state. He has found, in the progress of the 

 geological survey of Kentucky, that there are everywhere 

 across the area evidences that the coal-bearing strata were 

 at one time continuous. In numerous localities, at altitudes 

 of from 250 to 300 feet above the nearest streams, are found 

 debris, evidently derived from the coal -formation. These 

 include numerous masses of cannel-coal, with fragments of 

 the characteristic sandstones and conglomerates, and in some 

 cases organic remains, which leave no doubt that these were 

 derived from rocks of the coal-period ; while farther to the 

 southward were found evidences of the underlying millstone- 

 grit. He points out that the conditions in which these oc- 

 cur are such as to exclude the notion that they are of the 

 nature of drift, and maintains that they have been left by 

 the waste of these formations by atmospheric agencies. 



Newberry, in a recent report of his observations made 

 in 1859, describes a similar remarkable example of erosion 

 on a grand scale in the upper part of the Colorado plateau. 

 Here, resting conformably upon the Carboniferous limestone, 

 are the variegated sandstones and shales of the Lower Meso- 

 zoic, which pass upwards into the massive sandstones of the 

 Lower Cretaceous. Above these were once spread not less 

 than 2000 feet of soft shales belono-ino- to the Middle and 

 Upper Cretaceous, of which there now remain over great areas 

 only occasional mounds of the strata, and vast numbers of 

 organic remains scattered over the surface, the great mass 

 of strata having been worn away by subaerial agencies. 



