INDUSTRIAL PROGRESS DURING THE YEAR 1875. cvii 



well-known " bad lands " of that region. Another miocene 

 basin exists in Central Oregon, in great part concealed under 

 more recent basaltic rocks. These strata, which are more or 

 less inclined, and have a thickness of not less than 5000 feet, 

 include in their lower portions a fauna regarded as miocene, 

 but more ancient than that of the White River basin, which 

 is, however, represented in the upper portions of the Oregon 

 basin. Lying in part over the first-named miocene basin was 

 a great pliocene lake, having nearly the same limits as it to 

 the north and west, but with an area about five times as 

 large, and extending eastward and also southward nearly to 

 the Gulf of Mexico. The deposits of this pliocene area, 

 known as the Niobrara basin, attain a thickness of 1500 feet, 

 and contain organic remains which indicate a warm temper- 

 ate climate, while that of the eocene was tropical, and that 

 of the miocene intermediate between the two. The great 

 erosion which all this region has suffered is well set forth by 

 Dr. Hayden, when he states that from 10,000 to 15,000 feet 

 of strata, from the paleozoic upward, have been removed, 

 leaving only " what may be called remnants behind, occupy- 

 ing restricted areas. The hard and compact limestones of 

 the Silurian and Carboniferous ages are found to a greater 

 or less extent all over the Northwest. They yield much less 

 readily to erosion than the more modern rocks, and are con- 

 sequently to be found on the summits of the largest mount- 

 ains 10,000 and 12,000 feet above the sea." 



Dr. Newberry, in his lately published volume of the geol- 

 ogy of Ohio, has given a full and careful discussion of all the 

 facts known with regard to the superficial geology of the 

 6tate and the adjacent regions, and has connected them with 

 the hypothesis of land-glaciation. Professor Dana has given 

 his views with regard to the former existence and extent of a 

 great New England glacier. 



Mr. George M. Dawson has studied the physical geography 

 and superficial geology of Central Canada between the 

 Rocky Mountains and the great Laurentian axis, which from 

 Lake Superior stretches northwestward to the Arctic Sea. 

 Rising from the lowest plateau of the Red River and Lake 

 Winnipeg, 800 feet above the sea, we have to the west the 

 Great Plains of the middle plateau, 1600 feet above the sea, 

 and the third or western plateau rising to from 2500 to 4000 



