316 



Scientific Geology. 



5. Granular Quartz and Scapolite, containing also tremolite and 

 augite. (No. 544.) This variety is scarcely worth noticing. 



The strata of scapolite rock in Canaan run in a direction not far 

 from northwest and southeast, and dip to the northeast at an angle 

 generally as great as 45°. The principal part of the rock seems to 

 lie between the dolomitic limestone beneath, and the mica slate above 

 which forms lofty ridges of mountains in Canaan. I saw none of the 

 scapolite rock in place, however, more than 200 feet above the lime- 

 stone, though bowlders of it are frequently met with on the moun- 

 tain east of South Canaan meeting house to its summit, on the road 

 to Norfolk. I did not see the actual junction of the mica slate and 

 scapolite rock, but the dip and situation of the two rocks renders it 

 almost certain that the latter does pass under the former. On the 

 lower side, the scapolite rock passes by a gradual mixture into the 

 limestone ; as the specimens will show. Upon the whole, the age of 

 this rock is the same as that of the Berkshire limestone, which alter- 

 nates with mica slate ; and which probably is not as old as that which 

 alternates with gneiss. 



It will be seen that the preceding description of this rock does not 

 differ — except in being more extended — from that which I gave in 

 1828, in the 14th Vol. of the American Journal of Science. If I 

 could have referred it to any known group of rocks, I should not 

 have described it as new. But this was impossible. 



9. QUARTZ ROCK. 



Among the older rocks geologists have not been able to discover 

 any determinate order of superposition ; although each one of them 

 is most likely to be found in a particular connection. But the same 

 rocks are also found in several other connections, so as to render all 

 attempts to fix their exact place in the scale unsatisfactory. Our 

 rocks are as unmanageable in this respect as those in Europe, but no 

 more so ; showing that the same general causes have produced them 

 on both continents. I have already shown that our limestones are of 

 various ages, and the same is true of quartz rock, hornblende slate, 

 and some others. Amid this great uncertainty as to the place in the 

 series which the older rocks ought to occupy, it is not easy to decide 

 what is the best order of describing them. It will be observed that I 

 do not follow exactly the same order in the account of the rocks 

 which I am now giving, as is followed in the tablets attached to the 



