DIVISIONAL PLANES. 513 



part, where the area covered is as much as two square miles (0. B. A.), in Waterbury and Lowell. Trap 

 dikes have been noticed and will be described in the talcose schist, in the towns of Newbury, Warren, 

 Stockbridge, Bolton, Richmond and Enosburgh. Dikes are comparatively few in the talcose schist regions. 

 The concretionary granite is found in the talcose schist in Waterford, Northfield and Proctorsville. In the 

 southeast part of Huntington there is a coarse syenitic rock. 



Divisional Planes. 



The principal class of divisional planes in this formation are joints. Cleavage is rarely 

 seen, unless we have greatly overlooked its indications, and we have certainly labored 

 hard to find them, with but little success. Foliation may be found, but we think that in 

 general it corresponds with the planes of stratification. Except in a few cases, and many 

 of those in a coarse talcose conglomerate on the borders of the west range of talcose schist, 

 described under talcose conglomerate, we have found no planes referable to foliation 

 distinct from the strata. These cases are described and figured under the details of that 

 rock. 



The conjecture may arise in many minds that perhaps the original planes of stratifica- 

 tion have been entirely obliterated in this and some other metamorphic rocks, so that our 

 efforts to measure the thickness of the strata is utterly futile, and the results monstrous. 

 But we are not satisfied with the theory that foliation, or any other known cause can so 

 completely separate the different kinds of rock into separate bands associated with each 

 other, that they cannot be distinguished from what are universally admitted to be strata. 

 Can foliation separate beds of limestone, steatite, and serpentine, from the schists, causing 

 them to lie at right angles to the original strata ? This must be admitted if it is held 

 that the apparent strata of the metamorphic rocks are not the true strata. If otherwise, 

 the difficulty from the great thickness will still remain ; for many of these beds are per- 

 pendicular, as well as the adjoining schists. 



If it were possible that the original strata were from two to four feet thick, there are 

 joints in a few localities, thus remote from one another, dipping at a small angle. But 

 they are irregular, and frequently are not parallel to one another ; and moreover, the rapid 

 changes of their inclination militate against the supposition that these planes could ever 

 have been the boundaries of strata. Upon the whole, then, we cannot depart from the 

 old theory of the true dip and strike of the strata of at least the talcose schist, without 

 violating other geological laws of greater importance ; and we must, therefore, adopt un- 

 flinchingly whatever results may flow from it. 



We have taken a few observations that we venture to call foliation or something anal- 

 ogous to cleavage planes, in distinction from the true strata. Both these observations 

 and those of the joints were taken by C. H. Hitchcock, and hence it is unnecessary to add 

 the initials of his name to each observation according to our custom after the general 

 statement. 



[The locality, strike, dip of cleavage, and dip of strata are given.] 



Hydepark, strike N. 37 E., dip of cleavage 73 E., dip of strata 90. East Hydepark, strike N. 37 E., dip of 

 cleavage 73 W., dip of strata about 90. Wolcott, strike east of north, dip of cleavage 75 E., dip of strata 90. 

 Richmond, strike transversely to the strike of the strata. 



It is remarkable that these planes have a smaller inclination than the planes of stratification. 



