SCIENCE. 



571 



English geologist, Mr. Thomas Belt, this legend may 

 .have had some foundation in the former existence of a 

 continent, now submerged beneath the Caribbean sea, 

 through which the peaks represented by the Lesser Antil- 

 les, constituted a mountain chain. Local disturbances have 

 certainly affected this area, but we fail to find any evi- 

 dence of corresponding disturbance in the Cretaceous 

 strata of our southern States, except perhaps in con- 

 tinental elevations and depressions. Messrs. Guppy, 

 Gabb, and others have studied the rocks of the region, 

 but, up to this time, no one trained to the examination 

 of the difficult phenomena and problems under dis- 

 cussion. 



Nov. 14, 1881. 

 The President, Dr. J. S. Newberry, in the chair. 

 Twenty-four persons present. 



A paper was read by Dr. Alexis A Julien on 



THE EXCAVATION OF THE BED OF THE KAATERS- 

 KILL, N. Y. 

 (ABSTRACT.) 



This paper was supplementary to one read before the 

 Academy two years ago, concerning the phenomena of 

 erosion, glaciation, etc., in the Catskill Mountains, in the 

 vicinity of the Kaaterskill Clove. 



Flexure of Strata. — Prof. James Hall has indicated 

 the existence of four lines of flexure, running from N.E. 

 to S.W., the synclinals occupying the summits of ranges, 

 and Prof. Arnold Guyot locates one of these at Slide 

 Mt. The dips at the entrance of the Clove vary from 8° 

 to io° to the W. N.W., becoming only 3 four miles to 

 the westward, i. e., more neatly horizontal towards a 

 shallow synclinal fold supposed to occupy Hunter Mt. 



One ot the most interesting discoveries of Guyot was 

 the linear series of three maxima of altitudes above 4000 

 teet, Slide Mt.; Hunter Mt. and Black Dome. The gen- 

 tle flexure of the whole stratum required to produce this 

 line of maxima may be thus shown in the range running 

 S.E. and N.W. through Hunter Mt., 35 miles long. To- 

 ward the S.E., the descent from the crest of Hunter Mt. 

 (Alt., 4038 feet), to Overlook Mt. (3150 feet), is 888 feet, 

 in g}4 miles, equivalent to 1 in 56, or about i° ; toward 

 the N.W., from Hunter Mt. to Utsyanthe Mt. (3203 feet) 

 the descent is 835 feet in 25 miles, equivalent to 1 in 158, 

 or less than %°. 



Another similar series of maxima, however, occurs fur- 

 ther to the westward, consisting of Graham Mt. (3886 

 feet), Bear-pen Mt. (3545 feet), and Ashland Pinnacle 

 (3420 feet), distant respectively 9, 12, and 15 miles west- 

 ward of the former series. This southward convergence 

 of the axes of these two folds may probably account for 

 the increased protuberance and greater elevations in the 

 Southern Catskills. 



Newly determined altitudes. — Many new determina- 

 tions havejaeen made of points in the vicinity of the 

 Clove by means of an excellent aneroid, with constant 

 reference to the numerous stations in the vicinity whose 

 altitudes have been accurately obtained by Guyot. A 

 few are here subjoined : 



Hotel Kaaterskill, on South Mt 2466 



Parker Hill, summit 2565 



Parker Mt., " high ledge." 2874 



Clifton House 2101 



Newman's ledge, on North Mt 2486 



Gap between E. and W. peaks, North Mt 3116 



Toll-gate on Mt. House road ... 760 



Glaciation of summits. — All the crests near the Clove 

 have been now examined. On none above an altitude of 

 2900 feet have glacial stria; been found, in part because 

 they consist of thinly laminated flags deeply disinte- 

 grated by frosts. The highest striae discovered were 

 found on Parker Mt., "High ledge" (2874 feet), run- 

 ning S. 18° W. (magnetic), and under the roots of a large 

 tree on the SE, slope of Round Top, at an elevation of 



2871 feet, running S. 35° E. However, in all cases, a 

 matked difference exists in the slope of different sides of 

 a peak, the E .and S.E. sides presenting a precipitous face, 

 and the other sides more or less of a gentle slope. 



The highest striae yet found in the Catskills occur on 

 Overlook Mt., at an elevation of about 3100 feet, imply- 

 ing a depth of ice in the Hudson river glacier of about or 

 at least 3200 feet. Within the Kaaterskill basin, several 

 miles distant from the Hudson valley, the overflowing ice 

 stream became shallower, having an altitude of about 

 3000 feet. It thus appears that the surface of the glacier 

 inclined westward over these mountains, with a slope of 

 200 feet in 3 miles, 1 in 84, say about 



The conclusions of the former paper have been con- 

 firmed by recent observation, viz., that two glacier streams 

 have swept over these mountains, the Continental Glacier 

 from the N. W., submerging and carving out the highest 

 peaks, and the Hudson Valley Glacier from the N., later, 

 more shallow, bearing along vast quantities of materials 

 derived from the crystalline and lower Silurian rocks of 

 the Adirondacks and of the Helderberg Mts., and strew- 

 ing the whole region with their boulders ; and that no 

 local glaciers have existed in the Catskills after the retreat 

 of the Hudson Valley Glacier. 



Tilting of the Catskill plateau. — In the previous pa- 

 per an explanation had been given of certain facts which 

 seemed to indicate that the whole formation had been 

 gently inclined to the East and then to the South-east, 

 before assuming its present W. N. W. inclination, at a 

 period far anterior to the Glacial epoch. A profile sec- 

 tion of the ancient Kaaterskill valley, was exhibited, reach- 

 ing from Haines' Falls nearly to the junction of the N. and 

 S. branches of Schoharie creek, proving the gentleness of 

 the slope, the absence of rock, and the existence of a deep 

 and narrow buried canon, now filled up with moraine ma- 

 terial and a capping of peat. 



A comparison of the altitudes of Prattsville (1164 ft.), 

 a point on the Western axis, 12 miles distant from the 

 Kaaterskill Clove, and of the lip of the stratum above 

 Haines' Falls, (1857 ft.), at the head of the Clove, shows 

 that a depression of the latter point below a line connect- 

 ing these two points, even to the extent of a single de- 

 gree, would cause a descent of nearly 700 feet from 

 Prattsville to Haines' Falls, t. e., toward the East. The 

 excavation of the deep Kaaterskill and Plaaterkill Cloves 

 could hardly have been effected by the small streams now 

 occupying their beds. It is more probable that the Scho- 

 harie creek formerly flowed, at a higher level, to the east 

 into the Kaaterskill Clove, and afterwards to the south- 

 east into the Plaaterkill Clove, before the latest tilting of 

 the plateau to the VV. N. W. caused a reversal of the flow 

 of the stream, in the very opposite direction, through the 

 greater part of the same valley. An objection to this 

 theory presented itself in the obstacle which has created 

 a turn to the S. W. in the North branch of Schoharie 

 creek, near its junction with the South branch. But on 

 recent examination this was found to consist not of rock 

 but of a huge mass of coarse moraine material deposited 

 during the Glacial period on the southern slope of the 

 Schoharie valley. 



Sculpture of the plateau. — In a terrane consisting of 

 strata which dip at varying and perhaps very high angles, 

 the carving out of ranges and production of ravines and 

 gaps may generally be assigned to the occurrence of 

 flexures, of dykes or faults, or of beds whose material is 

 unusually solt, fragile, or rich in minerals of easy decom- 

 position. But the problem of topographical sculpture is 

 less easily solved in a stratum like that of the Catskills 

 consisting of a regular succession of layers which are 

 horizontally homogeneous and from which the phenomena 

 of disruption are absent. The original disintegration 

 and erosion of the mass which resulted in the produc- 

 tion of the ranges was perhaps mainly influenced by the 

 direction of the jointage. With this the trend of the 

 ranges in the vicinity of the Kaaterskill Clove appears to 



