572 



SCIENCE. 



coincide. The ravines, cloves, and deepest notches and 

 valleys may be attributed to the streams of the present 

 hydrographical basins, or to those connected with the 

 ancient eastward and south-eastward inclination of the 

 stratum already considered. But recent observatiors on 

 the juxtapos tion and coincidence of the highest gaps in 

 successive parallel ranges may possibly indicate the rem- 

 nants — in cross-section — of the beds of anc ent streams 

 at that level (about 3000 feet); this conclusion, if con- 

 firmed, would signify an inclination of the plateau to the 

 N.N E. (or to the S.S.W.?) at a still earlier period, that 

 immediately succeeding its elevaiion. 



Karnes. — In the upper basin cf the Kaatei skill, several 

 isolated hills of gravel, etc., cccur at an altitude of 1924. 

 feet, especially on the bank of the stream near the h^ad 

 of the Clove, which are probably kames; their materials, 

 though largely angular, show traces of imperfect stratifi- 

 cation. Near " Blythewood," on the North branch of tlir 

 Schoharie creek, a curious conical and steep isolated 

 kame rises 102 feet above the stream, made up of 

 rounded pebbles of the Catskil! grit, rarely a foot in 

 length, overlying a layer of coarse moraine. Its elevation 

 above the sea (1944 feet) exceeds that of any other kame 

 yet observed, those of the Fintry Hills in England reach- 

 ing 1280 feet, and those of the Androscoggin Lakes, in 

 Maine, 1600 feet. A very interesting series of from eight 

 to twelve very low kames — like parallel ridges, often 

 curving, made up of large rounded boulders — was also 

 found to follow the course of the Kaaterskill near Palen- 

 ville, in the Hudson Valley, at the mouth ot the Clove, 

 at an elevation of about 700 feet ; these probably mark 

 the course of the sub-glacial stream which issued from 

 the mouth of the Clove. The paper concluded with 

 observations on a deposit of laninated sand underlying 

 the ground moraine : on the feeble erosion of the slopes 

 of the Clove during the period which has elapsed since 

 the close of the Glacial epoch ; and on a new section of 

 the strata of South Mountain obtained from a new road- 

 cutting. 



Discussion. 



Prof. E. C. H. Day observed that one portion of Dr. 

 Julien's remarks reminded him of an idea which had 

 struck him many years ago with regard to the surface 

 geology of a valley on the south coast of England, near 

 Charmouth, in Dorsetshire. 



The stream in the valley referred to finds its way to 

 the sea through a narrow pass, which, as attested by the 

 rapid wearing of the coast line and its present configura- 

 tion, could only have been of (geologically speaking) very 

 recent origin. How the valley could have been drained 

 prior to the existence of this outlet was a question which 

 might be met by various hypotheses, and one of these 

 was that there might have been a slight unequal local 

 change of level, sufficient to have had the effect of tilting 

 the surface of the valley so that its waters were shed then 

 in a direction opposite to that which they now take. 

 This was nothing more than the veriest hypothesis made 

 many years ago. without any subsequent attempt at veri- 

 fication. It may suggest, however, the possibility of 

 such slight local changes occurring, in addition to the 

 greater movements already distinctly recognized, and the 

 desirability of careful invest gation to discover whether 

 such may not be traced in the altered direction of streams 

 and in the existence of ancient and unused water 

 courses — even in our own m ighborhoods. It may be 

 added that such local tiltings of par.s of the earth's crust 

 would necessarily influence the course of subterranean as 

 well as of suba_-rial waters, thus altering the distribution 

 and force of springs at the surface. 



Dr. J. S. N'ewberry stated that the Catskills presented 

 a more complex bit of topography and geology, and one 

 that had been more discussed than perhaps any other of 

 similar area in the country. It was once supposed that 

 these mountains were composed of a single geological for- 

 mation, which, from this fact, was called the Catskill group; 



and it was supposed to be a detached table land, deeply 

 carved by erosion. The late Col. Jewett, of Albany, found 

 strata containing Chemung fossils in the Catskills, and 

 from this inferred that the mountains were composed of 

 Chemung strata. Prof. Hall and Prof. Guyot, with their 

 assistants, then made a careful study, running through 

 several years,, of the topography and geology of all the 

 surrounding region. Their labors established the fact 

 that the Catskills are not an isolated mountain group, but 

 belong to the Alleghany system and are formed by a series 

 of folds or arches composed of the Chemung and Cats- 

 kill rocks. Of these folds, the convex arches, as is usually 

 the case, were cracked and broken and, therefore, yielded 

 readily to erosion, while the concave arches, protected 

 and solid, yielded less readily and, in time, by the wear- 

 ing away of their surroundings, were left in relief, form- 

 ing ridges with a synclinal structure. Hence it will be 

 seen that the topography of the Catskill region is chiefly 

 the resu't of erosion. 



So far as regards the changes of level from subterran- 

 em causes, referred to by Mr. Julien, it would certainly 

 be strange if the foundations of the Catskills were proved 

 to be stable. The old name, "terra firina," once applied 

 to the crust of the earth, is a complete misnomer, and it 

 is really a type of instability. Probably throughout the 

 globe local subsidence and elevation are constantly in 

 progress. In the interior of continents we have no evi- 

 dence or measure of these, but along coast lines the 

 water line tells us that changes are constantly and every- 

 where taking place, in the relative level of land and sea. 

 About New York the coast is sinking, though very slowly, 

 while further north, in places, it is rising, and Greenland 

 is sinking again. Back from the coast there is no such 

 nilometer, and yet we have no reason to suppose that the 

 earth is more fixed. Some indication is given by the re- 

 ports of those who dwell in mountainous regions, of 

 changes of level, which have shut from their view that 

 which was before visible or revealed what was before con- 

 cealed , but these observations have not been made with 

 accuracy and cannot be depended upon. 



In a recent paper before the Academy he had shown 

 the vast changes which had occurred along the coast in 

 this vicinity, viz., that the land once stood 600 feet 

 higher than at present : that the Hudson river had then 

 flowed by the city through a channel from 300 to 500 

 feet deep, now in large part silted up : that the Palisades 

 then stood from 700 to 800 feet above the river : that the 

 Housatonic then flowed through the East river into New 

 York Bay : that a sub-tropical climate then prevailed 

 throughout this region, with a varied and rich fauna and 

 flora, extending up even to the Arctic Sea: that then a 

 depression of the temperature and great change in the 

 climate ensued, with a corresponding alteration of the 

 fauna and flora; but that these changes were very slow 

 and progressive — the snows, which at first rested tem- 

 porarily upon the Catskill Mountain summits, became at 

 last permanent, and resulted in local glaciers. These 

 glaciers produced extensive erosion, cutting the channels 

 along which they moved, deeply. A partial obliteration 

 of their work then ensued through two agencies. First, 

 a continental glacier advanced southward, overtopping 

 all the mountains, grinding down the asperities of the 

 surface, filing old valleys, and banking up a great mass 

 of debris along its margin — a part of which is now 

 Long Island. Afterward, the climate becoming milder, 

 local glaciers were again formed similar to those which 

 preceded the great Glacier, and partially obliterated or 

 modified the results of the ancient erosion. It is a com- 

 plex problem now to distinguish between the phenomena 

 which have been respectively produced by all these 

 glaciers in varied succession, by the erosion of streams, 

 by flexures of the earth's crust, etc. 



The excavating power of glaciers had been denied by- 

 Prof. Whitney, but ice, hundreds of feet and sometimes 

 miles in thickness— as it was in the old glaciers— moving 



