1218 



NEW YORK STATE MUSEUM 



Through the point marked J on the map, plate 2, passes the 

 axis of the western anticlinal arch, on the crest of which are 

 exposed ledges of Coeymans limestone that show in the field on 

 top of the hill overlooking the Vertical cut. These Coeynians 

 beds dip slightly toward the northwest. A short distance down 

 the northwestern slope of the hill the New Scotland beds are 

 found, and near the foot of the hill the steeply dipping Becraft 

 limestone has been quarried in the Vertical cut [V-V, pi. 2]. 

 The limestone in the Vertical cut stands nearly on edge, with 

 a strike n. 75° to 80° e., and its apparent thickness is somewhat 

 increased by a virgating series of several minor thrust faults. 

 These faults radiate from an axis parallel to the strike of the 

 limestone and located a short distance below the floor of the 

 quarry, they cut the bedding planes of the limestone at low 

 angles, and in each case the upward thrust is on the north- 

 west side. 



The bowl-shaped area just north of the point J is filled with 

 drift deposits, so that its substructure can not be determined. 



4 The Vlightberg overthrust 



The western and northern edges of this overthrust plane are 

 marked on the map [pi. 2] by the heavy black line 2-2, and its 

 position is roughly indicated on section 2 [pi. 3]. 



On the south side of Delaware avenue, just beyond the shaft 

 house of the Spring quarry incline, there is a knoll showing an 

 anticline of Coeymans limestone, the axis of which points south- 

 westwardly across the fields toward the Vertical cut. The path 

 that crosses the east side of this knoll leads under the cliff of 

 New Scotland limestone on the north side of the Vlightberg 

 and then joins the lane that runs to the tenant house on the 

 hilltop. On the northwest side of the lane is a field with no 

 outcrops of rock. The lane itself runs over Coeymans limestone 

 which outcrops at intervals, dipping to the east at low angles. 

 Along the left or eastern side of the lane the New Scotland 

 limestone of the low cliffs is very much shattered and dips 

 steeply to the northwest. Continuing on up the lane, the Man- 

 lius limestone, with strike n. 20° e., dip 10° e., appears at the 

 point K on the map, at the angle of the road where it turns up 

 the hill toward the house. A little farther on, a low escarp- 



