J.D. Dana —Taconic Rocks and Stratigraphy. 215 
the open area between the mountain and the spur, where a 
limestone plain begins, the limestone comes out from beneath 
the slates of the mountain almost horizontally (see T-symbols 
on the map), and disappears in a similar manner beneat the 
slates of the spur with a dip slightly eastward. The inferior 
position of the limestone is plain. On the east side of the spur, 
along the Harlem railroad, where the spur joins a schist ridge 
of northeast trend, the limestone overlies the schist with a dip of 
30° (the direction of dip N. 18° E.) ; the proof of the underlying 
position of the limestone being accepted, this overlying lime- 
stone indicates only a westward careening of the synclinal—the 
usual fact, 
g. The evidence that Mt. Washington is a synclinal in struc- 
ture (or rather a compound synclinal), as already explained in 
the last volume of this Journal, is well shown on the map; an 
as the roads are given, it exhibits the facts more intelligibly to 
the reader than the map of the former paper. Along the west, 
side, eastward dips are universal in both the limestone and 
schist, and the angle is mostly between 40° and 60°. Along 
the-eastern foot the angle of dip in the schist and the nearest 
limestone is small in Massachusetts, being 10° to 15° westward 
— tthe north extremity in Egremont; 10° to 25° W. along by 
Spurr’s (see map), and about the same in the bluffs near peed 
In this Massachusetts part, in which the synclinal has a broa 
fo i 
the line. —_ 
South, west of ore-pit 7 (Camp’s) the dip is about vertical, an 
West of the ore-pit h ‘Sooville’) i has 10° ofeasting. The ae 
‘sg of Mt. Washington is hence shallowest to the north ; and, 
tke all the rest, is not a symmetrical trough. eh 
, igure 2 in the Mt, Washington paper (page 271) repres 
- Position of the rocks at 17 on the map, near L. eee of 
W, , that on the west side of the mountain at 18, 
’s ore-pit. The above figure 9, represents a sec 
