MUSEUM OF COMPARATIVE ZOOLOGY. 211 



condition ; while the gmy variety (3) is generally comparatively solid, 

 but occurs in a few places in the last stages of disintegration. 



From the shores of the Basin Pond, where an unobstructed view is to 

 be had of the whole height of the walls, the granite, up to two thirds the 

 height of the eastern side, or about the upper limit of the gray variety, 

 is seen to be arranged in concentric sheets, that dip west at an angle 

 varying from 45° to GO". On the southern wall the same concentric 

 arrangement prevails, the layers dipping north, often at angles higher 

 than G0°. Above the part that lies in concentric sheets is the red 

 granite, which divides, on weathering, into blocks more or less regular 

 in form. Near the head of a torrent that comes down from the Saddle, 

 in two instances the red variety (o) lies in blocks, with forms so definite 

 as strongly to resemble courses of cyclopean, but crumbling masonry. 

 At the foot of these " castles " the rock is so friable as to fall into gi-avel 

 under the tread. 



"What has been said of the occurrence of the red and gray granites, at 

 different elevations, does not mean that they are separated from each 

 other by any well-defined horizontal plane. ' They are undoubtedly parts 

 of one and the same formation, and, as in the quarries of Quiucy and 

 Cape Ann a variety of rock having one color passes into a variety of 

 another color so gradually that the separation cannot be said to take 

 place along any line, or plane, so at Ktaadn the red and gray granites 

 merge into each other in the same way, and at various levels. Yet it is 

 substantially true that the lower two thirds of the basin walls, and 

 probably the whole of the mountain mass below the level of the basin 

 floor, consist of the gray, and the upper 700 feet of the red granite. 



As has been remarked already, the granite of Ktaadn is singularly 

 free from dikes and veins. During the explorations made both in 1879 

 and 1880, not a dike or vein was discovered, either in the fi.xed or 

 loose rocks of the mountain. We have seen that the same was true, 

 with but two exceptions, of the ledges and bowlders that were obsen^ed 

 upon the Penobscot. The absence of these characteristics of older rocks 

 will be held to indicate that the granite of Ktaadn and its vicinity is of 

 comparatively recent origin. 



The only considerable departure from the normal granitic type is the 

 occurrence of very numerous inclusions which resemble imbedded frag- 

 ments of foreign rock. Like patches are common in most granites, but 

 I have never known elsewhere so many as the Ktaadn granite presents. 

 Upon the talus beneath the east wall of the basin a small block of red 

 granite was observed which contained five visible inclusions, varying from 



