652 THE POPULAR SCIENCE MONTHLY. 



to Nantucket. These strata still probably underlie a large part of 

 Long Island where they have been protected from erosion by the heavy 

 beds of drift that cover them, while the shore-waves have eaten away 

 all exposed portions. Evidence strongly confirmatory of the view that 

 Cretaceous rocks have been scooped out of the basin of Long Island 

 Sound is afforded by the fact that the drift of Long Island contains in 

 immense numbers imperfectly -rounded blocks of a reddish-broAvn sand- 

 stone, filled with the impressions of dicotyledonous leaves a rock no- 

 where yet found in place, but one which is probably the representative 

 of the leaf-bearing Cretaceous sandstone of the Raritan River. 



Whether the overlying Tertiary beds will be found on Long Island 

 is perhaps doubtful, since they are not conterminous with the Creta- 

 ceous ; but, from the fact that an outlier of this formation exists at Gay 

 Head, Martha's Vineyard, it is highly probable that it was once con- 

 tinuous from Southern New Jersey. 



On the preceding pages the history of the vicinity of New York 

 has been traced backward for some millions of years. This history has 

 been read from rock-graven records, which, although meagre and muti- 

 lated, give the generalities of the narrative with a truth and fidelity 

 which shame all human history. It would be a pleasant duty to pre- 

 dict the future of this region, even in the same degree of fullness ; but 

 the future is as unknown to the geologist as to others. He learns, 

 however, from his studies, that what we call terra firma is a type of in- 

 stability, and that there is nothing stable but the law of change ; and he 

 can prophesy with confidence that in the distant future the history of 

 the distant past will be, in part at least, repeated. Even now changes 

 are in progress which, if they should continue a few thousand years, 

 would very profoundly affect not only the aspects of this region, but its 

 adaptability to human occupation. A number of facts indicate that the 

 coast of New Jersey and Long Island is gradually sinking. From the 

 marshes of New Jersey are taken the trunks of trees which could not 

 have grown there except when it was drier ground, and on the shore 

 stumps are seen, now under water, of trees which must have grown on 

 land. So, too, the sea throws up in storms portions of turfy soil, once 

 covered only by the air, and similar soil has been reached below the 

 sea-level in pits dug through drifted sand along its margin. It is also 

 said that the land boundaries have been changed and farms diminished 

 even where the wash of the shore-waves produced no effect. The rate 

 of this subsidence is very slow only a few inches in a century and it 

 may at any time be arrested or reversed ; but, should it continue, as 

 it may, for some thousands of years, it would result in a submergence 

 of land now valued at hundreds of millions of dollars, and a complete 

 change of position in the seats of commerce and industry, which must 

 always centre about this harbor. This possible catastrophe is, how- 

 ever, so uncertain and remote that it seems hardly sufficient to disturb 

 the equanimity of at least this generation of inhabitants. 



