222 



NATURAL HISTORY OF VERMONT. 



Part I. 



GRANITE. GNEISS. 



MICA SLATE. 



CHAPTER VIII. 



GEOLOGY AND MINERALOGY OF VERMONT. 



When we commenced our undertaking 

 four years ago, we had little doubt that 

 there would be a Geological Survey of 

 the state, under the patronage of the gov- 

 ernment, in season to enable us to em- 

 brace the results of it in the present work. 

 In consequence of this expectation, we 

 have devoted less attention to the geology 

 of the state than to the other departments 

 of our natural history ; and, a survey not 

 having been undertaken, as we anticipa- 

 ted, we must content ourselves for the 

 present with only a few general remarks 

 on these interesting subjects. Enough is 

 already known to make it certain that our 

 state ranks among the first in the Union 

 in mineral resources, and by private and 

 individual enterprise something has al- 

 ready been done towards turning these 

 resources to account, as may be seen by 

 reference to our account of Strafford, 

 Pennington, Plymouth, and some other 

 towns in part third. The few remarks 

 which we shall offer will be presented 

 under the heads of Rocks, Metals, and 

 Minerals. 



nods. 



The ranges of rocks in this state, 

 for the most part, extend through the 

 state in lines parallel to the principal 

 range of the Green Mountains. The 

 greater part of the rocks are of primitive 

 formation. The ranges, commencing on 

 the west side of tiie state, according to 

 Prof. Eaton, are nearly in tlie following 

 order: — 1. Old Red Sandstone in an in- 

 terrupted range ; — 2. Graywacke ; — 3. 

 Transition, or Metaliferous Limestone, al- 

 ,ternating with Transition Argillitc ; — 4. 

 Transition, or Calciferous Sandstone : — 

 .5. Transition Argillite ; — 6. Primitive 

 Argillite ; — 7. Sparry Limestone ; — S. 

 Granular Limestone;-'J. Granular Quartz, 

 containing hematitic iron ore and manga- 

 nese, and lying at the foot of the 

 Green Mountains on the west side; — 10. 

 Hornblende Rock; — IL Gneiss, with al- 

 ternating layers of Granite; — 12. Mica 

 Slate, constituting the middle ridge of the 

 Green Mountains, and extending, in ma- 

 ny places, a considerable distance down 

 t\;e eastern side. Most of these ranges 



of rocks extend through the whole length 

 of the state; On the east side of the 

 Mountains the geological features are not 

 so well defined, nor so well known. Al- 

 though there are here indications of 

 ranges nearly parallel with those on the 

 west side, they are frequently interrupted 

 and jumbled together; the diff'erent rocks 

 otlen being arranged in alternating lay- 

 ers. The principal ranges of rocks in 

 tlie central part of the slate are nearly as 

 exhibited in the following diagram of a 

 vertical section passing from east to west, 

 through Camel's PLimp : 



1 2 3 4 



References. 



c. Slates, Graywacke, 

 Aigilliiceous, &.C. 



/. Mica Sl.ite. 



g. Quartz, Talcose Slalo 

 and Chlorite. 



i; Argillaceous Slate. 



Ic. Granite. 



i. L.ii»e. 



m. Argillaceous Slate. 



1. Lake Chatnplain. 



2. Camel's Hump. 



3. Moiitpclier. 



4. Connecticut River. 



a. Sanilstone. 



b. Argillacodus slate. 



c. Graywacke Sandstone. 



d. Limestone. 



Granite. This rock shows itself very 

 sparingly in the Green Mountain range, 

 and on the west side of the mountains 

 hardly exists at all, except in small rolled 

 masses. On the east side of the moun- 

 tains it occurs in many places in Wind- 

 ham and Windsor counties. In the north- 

 ern part of Orange county, the southeast- 

 ern part of Washington and southwestern 

 part of Caledonia county, it constitutes 

 tlie principal rock i/i si/ii. From this 

 great irranite region was obtained the ma- 

 terial tor building the State House. (S^s 

 Part- IJI., p. it.). Orleans county abounds 

 in huge granite boulders, which make 

 excellent building stone. 



Gneiss. This occurs in many places 

 along the summits of the Green Mountain 

 range and in the counties of Windham 

 and Windsor, where it serves a good pur- 

 pose for walls, under-pinnings, &c. 



Mira Slulc. This constitute.'^ almost 

 the entire middle range of the Green 

 Mountains from Massachusetts to Cana- 



