CALCIFEROUS SANDROCK. 269 



it unites with a spur that runs up to the very southern extremity of the town, upon the east shore of Lake 

 Champlain. This spur, represented upon Figs. 168 and 170, contains many beds of sandstone more than 

 the average. 



The southern prolongation of West Haven contains three different rocks, as already mentioned. Along 

 the west edge of this promontory there is quite a high range of hills, the highest of which is called Bald 

 Mountain. The rise from the west part of West Haven to the top of Bald Mountain is very gradual. 

 The north side of the highest peak is precipitous, but the range is not entirely cut off, for the hill still 

 continuing, terminates abruptly at the mouth of Poultney River. This countour of surface is due, not 

 to drift, but to the nature of the rocks, and perhaps elevation. The base of the highest summit is occupied 

 by gneiss, the oldest rock, the others probably overlying it. The abrupt southern slope of Bald Mountain 

 is probably connected with the elevation of the gneiss ; as the western side, which is precipitous, certainly 

 is. The range of hills is finally cut through at Whitehall by Poultney River, which made its way over 

 the more easily decomposing limestone as far as possible. 



Lake Champlain has cut a channel for itself through the calciferous sandrock for twenty miles, some- 

 times three hundred feet deep. Occasionally the gap is only just wide enough to allow the passage of the 

 steamboats, as at the narrows near the northwest corner of West Haven. The formation covers less width 

 of surface in the north part of West Haven, and in Benson, the height compensating for the width. 

 The southwest part of Benson, upon this rock, is mostly uncultivated, on account of its steep hills, and 

 deep narrow ravines. The staid uniformity of the limestone is broken at the northwest part of Benson 

 by the appearance of the drab colored variety, extending a quarter of a mile along the shore. With it 

 there is at length associated the ordinary limestone ; this presently gives way to the slaty variety, which 

 extends two miles along the shore, into Orwell, one mile south of Chipman's Point. Here the ledge is eighty 

 feet high, made up of a black glazed slate, from the decomposition of which calcareous tufa is constantly 

 forming. 



The eastern boundary of the calciferous sandrock is about two and a . half miles east of Benson landing. 

 Its western boundary reaches the base of the formation in Vermont only at the west foot of Mt. Indepen- 

 dence, in Orwell. There it is underlaid by a few feet of Potsdam sandstone, and the opposite side of the 

 lake is gneiss. At the southern extremity of Larrabee's Point in Shoreham the slate of the upper 

 portion of this rock may be seen upon the eastern side. It is exposed there in two low cliffs, that may be 

 reached by a boat. The dip is north, and the formation here bends westward, and crosses the lake to 

 Ticonderoga, N. Y. 



It is much thinner in Ticonderoga and Crown Point than in Vermont, and at Port Henry it is seen for 

 the last time, before its plunge under the lake. Here it is only a few feet thick. It re-appears two and 

 a half miles south of Westport, and extends for three miles, when it again passes under the lake. At 

 Split Rock it again appears, and extends far enough east to include perhaps one of the islands belonging to 

 Vermont, and the extreme end of the point adjacent. It continues from Split Rock to Clinton Co., N. Y., but 

 in very limited amount. At Plattsburg it begins to expand in breadth and thickness, reaching its maximum 

 in Canada, after which it passes southwesterly back into New York. 



The calciferous sandrock in the east parts of Orwell and Shoreham is elevated into an unnatural position . 

 At Orwell village it shows itself prominently, and is characterized by its thick beds and geodiferous masses. 

 One and a half miles northwest of the village Prof. Adams found, according to his note book, "abundant 

 fragments of trilobites and a small species of Maclurea" of this age. This rock shows itself upon the line 

 between Orwell and Shoreham, appearing there as a white metamorphic thick-bedded limestone. The 

 same rock appears directly east of Shoreham Center. At Rich's Mills in Shoreham, it is associated with 

 beds of sandstone twenty feet thick. At Newell's Mill in Shoreham, there are numerous fossils of the 

 genus maclurea and ophilata present in it. Between these two mills the characteristic variety of this rock 

 is well shown upon the west side of a large hill, by the side of the road. There is a deep gorge in the 

 vicinity, excavated in this rock by the Lemonfair River. Immediately cast of the sandstone, west of 

 Newell's Mills, this rock shows itself in great force. In this region there are several undulations, which 

 have not been traced north and south a great way, and thi-y are probably local. To this formation belongs 



