Trans. N. V. Ac. Set. 26 jVov. 14, 



observation, viz., that two glacier streams have swept over these moun- 

 tains, the Continental Glacier from the N. W., submerging and carvinoj 

 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 strewing 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 paper an explana- 

 tion 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 

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

 period far anterior to the Glacial epoch. A profile section of the 

 ancient Kaaterskill valley was exhibited, reaching 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 exis- 

 tence of a deep and narrow buried canon, now filled up with moraine 

 material 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 degree, would cause 

 a descent of nearly 700 feet from Prattsville to Haines' Falls, /. e., 

 toward the East. The excavation of the deep Kaaterskill and Piaater- 

 kill Cloves could hardly have been effected by the small streams now 

 occupying their beds. It is more probable that the Schoharie creek for- 

 merly flowed, at a higher level, to the eastward into the Kaaterskill Clove, 

 and afterwards toward the south-east into the Plaaterkill Clove, before 

 the latest tilting of the plateau to the W. 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 ths 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 plateati. — 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 w-hose material is 

 unusually soft, fragile, or rich in minerals of easy decomposition. But 

 the problem of topographical sculpture is less easily solved in a stratum 



