Geology &fc. of the Connecticut. 23 



that direction, as we have already suggested; although it 

 may not yet have made its appearance above the later rocks 

 the whole distance. 



This rock is somewhat Protean in its appearance; yet 

 not very difficult in most cases to be distinguished by care- 

 ful observation. The following varieties have been noticed 

 in this region. 1. A variety already referred to, as occur- 

 ring in Leverett, near the pudding-stone; which is scarcely 

 any thing more than imperfectly limpid quartz, divided into 

 distinct rhombic concretions, about an inch thick, and three 

 or four across the outside, slightly spangled or glazed with 

 mica. 2. Very much like the last, except that it does not 

 divide into complete rhombs, but is only separated by seams 

 oblique to the direction of the strata, and nearly perpendic- 

 ular to the horizon* — Locality, West-River mountain in 

 Chesterfield New-Hampshire. 3. Divided as the last by 

 two sets of parallel planes, forming angles with each other a 

 little oblique: But the mica is intimately disseminated in 

 fine scales through every part of the rock, and the quartz 

 becomes a mere siliceous sand, blended closely with the 

 mica. Surface rarely waving — Locality, Whately, Con- 

 way, &£c. 4. Not regularly divided in any direction, ex- 

 cept that of the strata, and much less fissile than the last. 

 Pilica scattered in fine scales through the mass, and the silex 

 more abundant than the last — Rock breaking into huge 

 blocks, from one to three feet thick, and often forming, like 

 greenstone, abundance of debris. Locality, West-River 

 mountain and Deerfield. These four varieties occur on the 

 borders of the secondary rocks. 5. Tortuous, wavy and 

 extremely irregular, embracing numerous beds and amor- 

 phous masses of quartz — Mica, very imperfectly character- 

 ised, forming a kind of glazing with the aspect of plumbago. 

 Locality, Conway, Shelburne, Colrain, &z;c. 6. Quartz and 

 mica in somewhat distinct layers — quartz predominating, 

 and mica not very well characterised — abounding in garnets 

 — Locality, Plainfield, Hawley, Conway, &c. 7. Passing in- 

 to talcose slate — mica abundant, having somewhat of a fi- 

 brous aspect and connected with talc. Northfield and Haw- 

 ley. 8. Passing into argillite. Locality, Leyden, Ches- 



*"When one set of parallel planes crosses another, are both sets to be cal- 

 led strata, or neither, or only one of them ?" — Grcenough's Geology, Essay \ . 



