54 



APPENDIX TO THOMPSON'S VERMONT. 



SUPERFICIAL DEPOSITS. 



DRIFT MATERIALS. 



LAWEEXCIAN DEPOSIT. 



Superficial Deposits. 

 Drift Scratches. 



The rocks which have been briefly descri- 

 bed, with the exception of our tertiary for- 

 mation, are all fixed in the places in which 

 they are foimd, and form the solid founda- 

 tion of our territory. The surface of these 

 rocks, where exposed to view, are every 

 where found to be ground, or worn down 

 by some agency, frequently having their 

 surfaces finely polished, and crossed by 

 numerous parallel strise, or scratches. 

 These striaj, or scratches, lying in the same 

 direction, in which the loose materials, 

 resting upon the solid rocks, have been 

 transported, are supposed to have been 

 produced by the movement of these materi- 

 als ; and, as the materials have received the 

 name of Drift, the strias, or grooves, are 

 called Drift Scratches. The general direc- 

 tion of these scratches, and of the transpor- 

 tation of drift materials, is towards a point 

 a little to the east of south, but varies in 

 different parts of the state, somewhat in 

 conformity to the directions of the valleys 

 and the ranges of mountains. 



The smoothing and striation of the sur- 

 faces of the rocks are most conspicuous, 

 when the earthy materials are first removed 

 from them. In some varieties of rocks they 

 are seen, in a great measure obliterated by 

 exposure to the weather. These polished 

 and striated surfaces are found, not only 

 in the bottoms of the lowest valleys, but 

 upon the tops of the highest mountains in 

 the state. Mount Washington, in New 

 Hampshire, appears to be the only point in 

 New England, which was not reached by 

 the agency which produced them. The 

 rocks, which form the summit of that moun- 

 tain, are all sharply angular, exhibiting 

 no appearance of having been worn, or 

 scratched. 



Drift Materials. — The smoothed and 

 striated solid rocks, which we have been 

 describing, are, in nearly all parts of the 

 state, covered by a deposit, very variable 

 in thickness, and consisting of boulders, 

 pebbles, gravel, sand and clay, variously 

 and irregularly blended together, without 

 any distinct signs of stratification. These 

 materials are, for the most part, different 

 fi'om the rocks on which they rest; and, as 

 they are usually accompanied by evidence 

 that they have been transported in a south- 

 easterly direction, they have received the 

 general name of Drift. In some places 

 the drift consists entirely of sand ; in other, 

 of clay; in others, of gravel; but these are 

 usually of small extent. The materials are 

 more commonly mixed, but in very differ- 

 ent proportions in different places. It is 

 quite common to find them in the condition 

 of what is called hard-pan, wherein sand, 



clay, gravel and pebble are so completely 

 bedded together as to make it extremely 

 difficult to penetrate them. 



The proofs that the drift has been trans- 

 ported in a southerly direction, and never 

 in a northerly direction, are very abundant. 

 The large boulders of sienite and other 

 rocks scattered through the valley of Lake 

 Champlain, have evidently been brought 

 from beyond the 45th parallel of latitude, 

 there being no rocks of their kinds within 

 the limits of the state. Boulders of Tren- 

 ton and Isle la Motte limestone are found 

 scattered along the western slope of the 

 Green Mountains, and resting on talcose 

 slate, far to the southeastward of the quar- 

 ries from which they must have been deri- 

 ved. Boulders of the red sandrock, which 

 is found in place only near the lake shore, 

 ai'e met with in masses, of several tons, in 

 Williston and Richmond, and high up on 

 the sides of the mountains, and even to the 

 eastward of these mountains. To the east- 

 ward of Camel's Hump, in Duxbury, there 

 is a boulder, which weighs about three 

 tons, and which very clearly came from the 

 lower strata of the red sandrock formation, 

 near the level of Lake Champlain. It is 

 now 20 miles from the nearest part of that 

 formation, and rests upon talcose slate, at 

 an elevation of about 700 feet above the 

 level of the lake. 



The transportation of boulders of what 

 we have called Nodular Granite, has already 

 been mentioned. They are found, of large 

 size, in Waterford, Ryegate, and other 

 places, 30 miles from any locality, where 

 the rock is in place. Instances might be 

 mentioned, where boulders of this rock 

 have been transported over deep v allies, 

 and lodged near the summit of the elevation 

 on the opposite side. 



LAWRENCL4.X DEPOSIT. 



Throughout the valley of the St. Law- 

 rence, the valley of Lake Champlain, and 

 around Lake Ontario up to the Falls of 

 Niagara, there is found a regularly strati- 

 fied formation of sands and clays, to which 

 has been given the name of the Laicrencian 

 Deposit. The thickest parts of this for- 

 mation, in the valley of Lake Champlain, 

 is about 200 feet, and the highest part of 

 it is, at least, 400 feet above the level of 

 the ocean. The southern portion of it con- 

 sists chiefly of clay, while in Franklin 

 county and the northei'n part of Chittenden 

 count}', sand predominates, particularly at 

 the surface. 



It is clearly a mai-ine deposit, being well 

 filled with remains of marine bivalve mol- 

 luscs and other animals ; and, as nearly, 

 or quite, all of these remains belong to 

 existing species, it is plain that it belongs 



