Notice of a Scientific Expedition. 335 



Materials forming the Coast. — Trap rocks form the coast for 

 about one hundred and thirty miles. The breadth of the range, 

 scarcely exceeds three miles. Beneath the trap is the new red sand- 

 stone, which occasionly appears in nearly horizontal strata. Reck- 

 oning in the upward order, the rocks are sandstone, amygdaloid and 

 greenstone. The lines of demarkation between these rocks are 

 remarkably distinct, so much so that they may be seen at a distance 

 of many rods. 



The amygdaloid is quite vesicular, more so, and more lava-like, 

 than that of Connecticut river. We speak of this character as gen- 

 eral ; many portions of it resemble so perfectly cinders from a forge, 

 that the difference would pass unnoticed by a cursory observer. 

 The greenstone, exhibits more or less tendency to a columnar struc- 

 ture ; it is compact, heavy, and sonorous when struck with a ham- 

 mer. Its compactness is, it appears to us, between that of the basalt 

 of the giant's causeway and of the greenstone of Connecticut river. 

 The particles of feldspar are less ; in fine, it is more homogeneous. 

 At no place which we visited, did we meet with any porphyritic green- 

 stone. This variety we have already remarked, occurs at Lubec, and 

 is known also to exist at various places in the valley of the Connecticut. 



Imbedded Minerals.- — There is a great uniformity in the distribu- 

 tion of the minerals. Amygdaloid is the repository of the zeolite 

 family, or the genus kouphone spar, while the greenstone contains 

 the silicious or quartz family. There are rarely exceptions to this 

 order of distribution. The only mineral known to belong to the 

 the sandstone is selenite or gypsum. 



Degradation. — The abrading action of the sea and of other de- 

 stroying agents, is not the least instructive phenomenon of this region. 

 The shores as has been remarked, are strewed with angular boulders. 

 They extend into the sea beyond low water, but how far, we were 

 unable to determine. From an inspection of the coast, it is easy to 

 see how this degradation is carried on. As the amygdaloid is the 

 rock which is exposed to the sea, and the action of its heavy tides, 

 the porosity of its structure, enables it to resist but feebly its furious 

 attacks. Cavities with shelving banks are formed which are sooner 

 or later crushed in by the enormous weight of the greenstone above ; 

 or the greenstone is forced from its perpendicular sides by water 

 freezing between its columns. As these shores have been exposed 

 for ages to these arid other kinds of destructive agents, no one can 

 doubt that great changes have been produced both in the configura- 

 tion of the coast, and in the width of the adjoining bay. If it is ad- 



