170 [ASSEMJ3LT 



as the most northern outcrop of Archaean rocks in the south-eastern 

 part of the State and as an island in the newer and Palaeozoic rock 

 formations.* 



II. East or [Dover] MouxTAiif. 



The mountain bordering the valley of Amenia and Dover Plains, 

 in Dutchess county on the east, is generally known as the East moun- 

 tain. East and south-east of South Amenia the more promment 

 peaks are known as " Peaked hill," and the " Cobble," the latter of 

 which is just over the line in Connecticut. The designation of Dover 

 mountain would appear to be more appropriate and definite, as this 

 range is the highest and most characteristic of the ridges in the town 

 of Dover. The north-eastern part is in Amenia, and it is a continua- 

 tion of the Sharon-Cornwall range, f The south-western end is 

 marked by the valley of the Webotuck. The part of the range 

 embraced within the State is only about nine miles long, from the 

 Connecticut line, east-north-east of South Amenia to the Webotuck, 

 east of South Dover. In the town of Dover the top is moderately 

 rolling and the whole mountain is a small table-land rather than a 

 single ridge or mountain range. 



The highest point of this mountain is near the Connecticut line 

 about a half a mile east of the Patchin neighborhood, and its altitude 

 above the level of tide water is reported to be 1,500 feet. The bar- 

 ometric observations on section lines which were followed during the 

 survey last autumn show the highest point observed to be near the 

 school-house in the " mountain district," and its height as 1,350 feet. 

 Tlie ''Cobble," which is a prominent peak in the landscape from the 

 Sharon and Amenia valley, was found to be about 1,400 feet high. 

 There are no deep gaps in the range and the surface inequalities are, 

 on the average, only about 200 feet, that is, from the ridges to bottoms 

 of the adjacent valleys. But looking off into the Dover Plains on the 

 west, and Kent Plains on the east, the boldness of the mountain and 

 the depth of these bounding valleys are at once conspicuous features 

 of the surface configuration. These valleys have an average height of 

 400 feet above tide, or are from 600 to 900 feet deep, as compared wutli 

 the mountain. The outer slopes, descending to these valleys, -are very 

 steep in places, precipitous, and hence they are in forest. On the top 

 of the mountain the less rocky and level or gently-rolling portions 

 near the road which cross the mountain from Dover Plains and South 

 Amenia to Kent Plains, Connecticut, have been cleared and inclosed 

 in farms. But this deforested area is comparatively a very small frac- 

 tion of the whole, and the mountain may be described as still wooded. 



The boundaries of the gneissic strata of this mountain range are 

 traced without difficulty, excepting near South Amenia, w^here the 

 border of the gneiss appears under the drift of the valleys. Begin- 



* Mather in his Geology of the First District yatural History of 2^ew York, 1S42, pp. 

 548, 612, has a brief notice oif the Stissing mountain rocks, in which he calls them Primary. 

 See, also, pp. 430, 437 of same report. 



+ Dr. Percival in his " Report on the Geology of the State of Connecticut," 1842, calls 

 this Dover-Kent-Sharon range of crystalline rocks or " granitic formation," and he repre- 

 sents it on his map by the designation of K., pp. 115-119. 



