724 



SCIENCE 



[N. S. Vol. XXXII. No. i 



sandy, and there is some evidence of the pres- 

 ence of water during deposition, such as oc- 

 casional sorting and bedding of the pebbles, 

 and intercalated lenses of sandstone. There 

 is indication of at least one brief period of 

 cessation of till deposition, with accompany- 

 ing deposition by water of a thin irregular 

 sheet of sand and mud. By later ice move- 

 ment this was over-ridden — apparently in a 

 direction from the east toward the west — de- 

 formed and partly broken up, and a consid- 

 erable further thickness of till deposited upon 

 it. Later in the day we revisited the Hyde 

 Park locality, where a quartzite pebble was 

 found, imbedded in the matrix, having a well- 

 developed " sole " or beveled face, upon which 

 are scorings in at least two directions, the 

 moulds of which show in the matrix. 



The tillite occupies the upper portion of 

 what has been known, as the Eoxbury con- 

 glomerate, and at Squantum is from 500 to 

 600 feet thick, and is overlain by about 60 

 feet of stratified conglomerate, sandstone and 

 interbedded slate, which make the top of the 

 Eoxbury and form a transition to the over- 

 lying Cambridge slate. The possible glacial 

 origin of the Eoxbury conglomerate has been 

 suggested by the late N. S. Shaler and others, 

 but these are the first known discoveries in 

 that formation of definite evidence of glacial 

 action or of the existence of glacially de- 

 posited beds. In the absence of determinative 

 fossils, the age of the Eoxbury and Cam- 

 bridge formations has never been definitely 

 known, but they have been assigned on gen- 

 eral grounds, chiefly the analogy of their 

 structural relations to those of similar beds 

 in the Narragansett Basin, to the upper part 

 of the Pennsylvanian Series, of the Carbonif- 

 erous System. In view of the accumulating 

 evidence of glaciation in many parts of the 

 world in Permian time, it seems a reasonable 

 assumption that if glacial conditions pre- 

 vailed in eastern New England at some time 

 late in the Carboniferous Period, they were 

 contemporaneous with similar conditions 

 elsewhere, and hence that glacial deposits 

 found in the Carboniferous rocks of the Bos- 

 ton region were formed in Permian time. 



There are no known grounds for objecting to 

 the assignment of a Permian age to the Eox- 

 bury and Cambridge formations, and in fact 

 such a view explains some of their observed 

 structural relations rather better than the 

 older view. In the opinion of Dr. Huntington, 

 the discovery of this tillite is the best evidence 

 yet brought to light upon the age of the Eox- 

 bury conglomerate. 



The above account will be followed shortly 

 by a "more complete, illustrated article. 



Egbert W. Sayles, 

 Laurence LaForge 



a contribution to the problem of coon butte 



It has seemed to the writer that the chief 

 difiiculty in the way of acceptance of the vol- 

 canic origin of Coon Butte has been an as- 

 sumed impossibility of breaking the grains of 

 the gray sandstone into angular fragments by 

 hot water action. If this can be done, the 

 former, though now subsided, volcanic activity 

 of the region within a few miles of the crater 

 would give a presumption of its formation by 

 such agency, especially as no meteorite large 

 enough to make such a crater has been found, 

 although searched for by Messrs. Barringer 

 and Tilghman by means of pits and borings. 



Dr. Merrill suggests that the impact of the 

 body developed heat enough to volatilize it. 

 This view does not seem warranted by what 

 we know of smaller meteorites whose falls 

 have been witnessed, but if heat of sufficient 

 intensity to volatilize a mass of iron, say 500 

 feet in diameter, could be so developed it 

 would surely leave undeniable marks in fused 

 and metamorphosed crater walls. No such 

 effects are to be seen. 



There are some features of the crater that 

 seem inconsistent with its formation by a pro- 

 jectile. The powdered sand grains come 

 mainly from the gray sandstone lying 200 

 feet or more below the surface while the red 

 sandstone cap, on which the body would have 

 fallen, and the yellow silicious limestone next 

 below seem chiefly to have been broken into 

 fragments. 



Again, of the powdered silica Tilghman 



