316 



SCIENCE. 



[Vol. II., No. 31. 



fully elicited. The general expression was to the 

 effect, that the theory had been framed without suf- 

 ficient observation of the facts, and tliat, if the author 

 had taken the trouble to see and examine various 

 canons, he would have come to a widely different 

 set of conclusions. 



The ancient glaciatioii of North America : its 

 extent, character, and teachings. 



BY J. S. NEWBEERT OF NEW YORK. 



While the glacial area on our continent has not 

 been fully explored, there is abundant proof for the 

 following propositions : 1°. Glaciers covered most of 

 the elevated portions of the mountain belts in the far 

 west as far south as the 36th parallel, and in the 

 eastern half of the continent to the 40th parallel of 

 latitude. 2°. The ancient glaciers, which occupied 

 the area above described, were not produced by local 

 causes, but were evidences of a general climatic con- 

 dition. 3°. They could not have been the effect of 

 a warm climate and an abundant precipitation of 

 moisture, but were results of a general depression 

 of temperature. 



The traces of glaciation are similar in kind, and 

 apparently in date, over the whole ai'ea: they are 

 therefore effects of general, not of local, causes. East 

 of the Mississippi, the evidence is even more wide- 

 spread and impressive than in the far west. The 

 area bearing marks of ice action, and strewn with 

 drift, extends from New England westward, parallel 

 with the Canadian highlands, in a belt five hundred 

 miles wide and over two thousand miles long. Its 

 northern extension has not been traced beyond 

 Winnipeg; but there are reasons for believing that 

 it reached to the Arctic ocean, and that the great 

 lakes are pre-glacial river-valleys, scooped out and 

 modified by ice. Fully half the continent north of 

 the 36th parallel was glaciated. So far as we now 

 know, the glaciation was synchronous. 



The iceberg theory was opposed by Dr. Newberry, 

 on the following grounds: It postulated a water-line 

 with irregularities of level that are irreconcilable. 

 The direction of the scratches, and the lines of devi- 

 ation of the bowlders, require that the northern por- 

 tion of the continent should have been all submerged, 

 leaving no land for the origin and starting-point of 

 icebergs. If the icebergs could have been formed 

 and floated, an incomprehensible tangle of ocean- 

 currents would be required to account for their move- 

 ments. The evidence of sea-covering, in the form of 

 marine shells, is totally absent from the great drift 

 area of the interior, while they are found abundantly 

 in the Chamislain and bowlder clays of the coast. 

 Finally, the inscription left by the eroding agency is 

 characteristic and sui yeneris. 



The record of the ice period on our continent is far 

 more extensive and impressive than it has been rep- 

 resented. The phenomena were due to an extrane- 

 ous and cosmical cause, not to any thing local or even 

 telluric. The question here passes from the geolo- 

 gist, and must be addressed to the astronomer. Pro- 

 fessor Newberry briefly recapitulated some of the 



theories which have been suggested by Croll, New- 

 comb, and others, to account for the glacial epoch. 



Result of explorations of the glacial boundary 

 between Neiw Jersey and Illinois. 



BY G. F. WKIQIIT OF OBERLIN, OHIO; 



After citing reasons for desiring a careful resume 

 of the subject, — the observations being scattei-ed in , 

 the works of different explorers, — the author pro- 

 ceeded to name those who had determined, for dif- 

 ferent regions, the southern boundary of the glacial 

 area. Starting at the eastern coast. President 

 Edward Hitchcock was the first to intimate that the 

 backbone of Cape Cod was a part of the terminal 

 moraine if the theory of Professor Agassiz were true. 

 Clarence King made a similar assertion as to ac- 

 cumulations near Wood's II oil and on the Elizabeth 

 islands. Professor Charles H. Hitchcock declared 

 that the backbone of Long Island was the foot of a 

 terminal moraine. Warren Upham went over this 

 field, from the end of Cape Cod to Brooklyn, to verify 

 the hypothesis. Professors Cook and Smock traced 

 the moraine across the state of New Jersey. Pro- 

 fessor Lesley commissioned Professor Carvill Lewis 

 and the author of the paper to continue the explora- 

 tion across Pennsylvania. In Ohio, Professor New- 

 berry has approximately outlined the boundary; but 

 in Ohio, Indiana, and Illinois, the survey was carried 

 on by a number of different persons before the most 

 distinctive glacial features were fully understood. 



The chief indications on which reliance can be 

 placed to determine glacial action are striated rocks, 

 striated stones, bowlders, and till. Eocks near the 

 margin are often so deeply embedded in till, that 

 their markings are not apparent. The softer rocks 

 do not always retain their striae : this has often been 

 the case in Ohio. In certain situations, stones might 

 be striated by a landslide, or the grounding of an 

 iceberg; but the area over which striated stones are 

 found is too vast for such explanation of their pres- 

 ence. The bowlders are of granite and metamor- 

 phosed rocks from northern Canada and the shores 

 of Lake Superior: their presence Is relied upon only 

 when they are on such high lines as to preclude the 

 likelihood of their having been transported by the 

 agency of rivers. Till is spread over the whole area: 

 it is defined as an unstratified deposit, containing 

 striated stones of various sizes, — fragments of rock 

 foreign to the locality. Its composition varies, 

 through mixture with underlying material. It covers 

 and gives fertility to northern Ohio, Indiana, and 

 Illinois. Till has been ch.aracterlzed by Professor 

 Newberry as the grist of the glacier. 



Briefly told, the boundary-line of the glaciated area, 

 so far as now accurately known, is as follows : Begin- 

 ning on the island of Nantucket, it runs through Mar- 

 tha's Vineyard, No Man's Land, Long Island from east 

 to west, across Staten Island, entering New Jersey at 

 North Amboy, and after bending northward and mak- 

 ing a right angle near Dover, crosses the Delaware 

 at Belvidere. Tljence it runs north-westerly through 

 Northampton, Monroe, Luzerne, Columbia, Lycom- 



