MUSEUM OF COMPARATIVE ZOOLOGY. 319 



The same. Fourth Annual Report, 1840. The Hudson River slate 

 group " is overlaid unconformably in many places by the various rock 

 formations of more recent origin." (p. 212.) The common and hydraulic 

 limestones at the base of the Helderberg series "sometimes rest uncon- 

 formably upon the PIndson slate group, as at Lawrence's quarry, on the 

 Rondout, opposite Wilbur (see fig. 6, copied from fig. 1, PI. 26, Final 

 Report, 1843) ; sometimes conformably on the Shawangunk grit, .... 

 as at Rosendalc and Lawrenceville, on the Rondout ; sometimes on the 

 red and variegated shales and grits that overlie the Shawangunk grits, as 

 at the High Falls of the Rondout in Marbletown." (p. 237.) Lawrence's 

 quarry is again mentioned (242) as affording " a fine exposure of the 

 different strata, and the Hudson slates are seen unconformable, below 

 the limestones." At Hasbrouck's quarries on Pine Mountain between 

 Rondout and Kingston Point, the Hudson slate series dips 40-60^ to 

 E. S. E. ; the overlying limestone and cement beds dip 80° W. N. W., 

 "and this dip continues nearly uniform along this line of upheave to the 

 'High Rocks' above Kingston Point." (p. 242.) 



The same. Fifth Annual Report, 1841. There is "a line of fracture 

 and anticlinal axis " extending northward from New Jersey, passing 

 Kingston and the district here mapped, " On the west side of this axis 

 of fracture and elevation, the rocks dip to the westward at variable, but 

 generally at small angles, while on the east side they dip at a high 

 angle to the eastward, and are frequently vertical in their stratification." 

 (p. 64.) Further reference to Becraft's Mountain is made on page 90; 

 it is also said that west of the line of fracture "the superincumbent 

 rocks overlie this [Hudson slate] series conformably in most places." 

 The several Helderberg outliers known to Mather are Becraft's Moun- 

 tain and Mount Bob near Hudson ; another in Greenbush, between the 

 Sandlake and Nassau roads, about two miles from Albany, first examined 

 by Dr. Eights ; and two others described by Eaton, one in the north 

 part of Greenbush, five miles southeast of Troy, the other in the town 

 of Schaghticoke, on the north side of Tomhannock Creek (p. 87). 



The same. Geology of New York, First Distrct, 1843. Most of 

 the observations are repeated from the Annual Reports, pp. 330-373. 

 Becraft's Mountain is described in detail (p. 351) and figured (PI. 24, 

 fig. 6, here copied, fig. 7) ; no doubt is expressed of the unconformity 

 there; but at Mount Bob (PI. 38, fig. 1, here copied, fig. 8) it is said 

 to be "apparent." "Although the actual junction of the rocks of 

 the Hudson River group with those of the Helderberg division was 

 not observed between Kingston and Catskill, they were seen in many 



