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NEW YORK STATE MUSEUM 



nel traversed part of the Port Ewen beds, and at increasing 

 distances from the mouth of the tunnel the bedding planes were 

 found to have flatter dips, which diminished from about 65° w. 

 near the hanging wall to about 30° w. at the blind end of the 

 tunnel. 



Above the western edge of the quarry [see pi. 13] is a wood 

 road in which ledges of Port Ewen limestone outcrop at in- 

 tervals, and at the foot of the escarpment west of the road 

 is the eastern edge of the overthrust. The position of this 

 thrust plane is indicated by the heavy black line in the photo- 

 graph. The escarpment above the thrust plane, imperfectly 

 shown in the woods at the left of the photograph, contains the 

 upper member of the cement series (Rondout beds) and the lower 

 portion of the Manlius limestone. A short inclined shaft was 

 sunk for the purpose of prospecting the cement beds, and this 

 incline affords some interesting data on the attitude of the 

 thrust plane. The hanging wall dips 30° w. at the surface, but 

 at 25 feet underground this dip flattens to 14° w. The foot wall 

 of the cement dips about 15° w. throughout, and this is con- 

 sidered to be the approximate dip of the thrust plane at this 

 point. 



About 250 feet west of this first escarpment, on the farther 

 side of a small valley eroded in the middle layers of the Man- 

 lius, is a second escarpment about 40 feet higher than the first 

 and capped by the basal layers of the Coeymans, which dip to 

 the west at a low angle. It was in this escarpment, at the 

 point where it is crossed by the path that leads from the north 

 end of the White lime quarry westward through the woods, 

 that the fossils described on page 1188 were obtained. 



Continuing westward along this section line, we cross a 

 second ridge of flat upper Coeymans beds, then a broad ridge 

 of New Scotland beds which present steeper inclination toward 

 the west, and at about 750 feet west of the road appear the 

 lower layers of the Becraft vein 2. The outcrop of this Be- 

 craft vein is wide because at its eastern edge the beds dip 

 about 30°, and at its western edge this dip suddenly increases 

 to 75°. Then on the crest of the ridge overlooking the western 

 slope of the hill is a belt occupied by about 110 feet of Port 

 Ewen beds with an 80° westerly dip. Halfway down the slope 



