442 MESOZOIC TIME — REPTILIAN AGE. 



harbor, showing deeper water along this line, and evidently 

 proving that once the land was above water, with the Hudson 

 River occupying this channel on its way to the ocean. At two or 

 three places along this channel there are " deep holes/' as they 

 are called (one of them at 32, where the depth is thirty-two 

 fathoms), which may have been former sites of New York harbor; 

 for the waters of the harbor are now about six fathoms deeper than 

 those about its entrance. 



This border, now submerged, has, therefore, in former time been 

 dry land ; it may have been partly so in the Triassic period, and 

 thus have caused the imperfect connection of the Triassic areas of 

 the Atlantic border with the ocean. 



The Triassic continent spread westward to Kansas, and south- 

 ward to Alabama ; for through this great area there are no rocks 

 more recent than the Palaeozoic. 



The Triassic beds beyond the Mississippi are remarkable for 

 their great extent and their paucity of life. They occur in 

 western Kansas on the' east, and along the Little Colorado west, 

 of the mountains ; and they have been observed at many points 

 between these distant meridians: it is therefore probable that 

 they cover a large part of the slopes of the mountains beneath 

 the Cretaceous and Tertiary rocks of the surface. The discovery 

 of animal fossils may yet be made in some part of this region. 

 Yet it is remarkable that the beds should have afforded thus far 

 no relics of marine life, unless the Saurian remains be an exception. 



There appears to be but one mode of accounting for the forma- 

 tion of such deposits over this wide territory. The interior sea in 

 which the Carboniferous limestone of the preceding age — even 

 wider in its limits — had been formed, must have become more shal- 

 low and have been cut off to a great extent from free communica- 

 tion with the ocean. Such a shallow salt sea, alternately freshened 

 and concentrated by the successive rains and droughts of a season, 

 would be quite unfit for ordinary marine life. Few species could 

 survive through such alternations ; and hence there would be 

 necessarily a paucity of fossils in the deposits. Examples of such 

 interior salt seas without marine life now exist. Lake Utah is one, 

 in the Rocky Mountains. A complete evaporation over any por- 

 tions would have deposited salt and gypsum, — the salt to be dis- 

 solved and carried off wherever the. region admitted of drainage 

 by outflowing waters, the gypsum to remain in the beds. 



Facts observed among the Pacific Coral islands, illustrating the 

 destruction of life alluded to, have been mentioned on page 250. 

 These islands exemplify also the origin of the gypsum. According 



