Perry.l 202 [April 19, 



these minerals (Mr. Burbank, I believe, was the first to notice their 

 presence in the limestone, on a previous visit) is a striking feature, 

 which may be verified by any visitor who is disposed to be sufficiently 

 pains-taking to go through with the task; while it is certainly well 

 deserving of attention, both in itself considered, and because of the 

 witness it bears in various directions. Indeed, the foliated structure, 

 with its accompanying series of mineral substances, each occurring 

 in a determinate order, evinces that the process of veinous deposition 

 was gradual, and probably long continued; that time enough must 

 have elapsed for one set of ingredients to be brought in and depos- 

 ited (for fresh supplies, containing some new elements, to be intro- 

 duced and exhausted), for these again to be superseded, or at least 

 supplemented, by additional and somewhat varying materials, them- 

 selves to be in their turn fixed upon the walls in leaf-like layers ; also 

 that one of these layers succeeded another in regular gradation, from 

 the sides of the cavities, which in some cases were many feet in 

 diameter, toward the centres, until all the interior spaces were finally 

 filled; and that consequently, the apparent stratification is due, not 

 to aqueous deposition, as ordinarily regarded, but to the vein-struc- 

 ture of the calcareous deposits. 



Again it should be remarked that limestone veins, and various 

 irregular apertures filled with carbonate of lime, of smaller size than 

 the main cavities already noticed, may be detected here and there in 

 the walls of the adjoining rock. Indeed, a careful inspection of the 

 quarries reveals the occasional presence of calcareous matter in what 

 were, perhaps, once minute clefts, cracks and crannies in the sur- 

 rounding gneiss; the presence of matter, which was no doubt intro- 

 duced into all the smaller crevices, in connection w,ith the deposition 

 of the principal masses of limestone, but long after the formation of 

 the main gneissic rock. This calcareous material which, in places, 

 may be now seen ramifying, in a vein-like way, the walls that form 

 the chief cavities, was evidently connected at some former period 

 with the larger masses of limestone. Such veins, while they are not 

 numerous, or likely to be noticed without careful scrutiny, are of 

 great interest and very significant. 



But this is not all; there is other, and what to some will perhaps 

 be more explicit, testimony to the former prevalence of a vein-form- 

 ing agency. An accurate observer, even the casual visitor, will 

 hardly overlook the marked conformity of the limerock with the 



