67 ' JOURNAL OF THE 



but the rock for several miles, as well as at this 

 particular locality, contains a multitude of rounded and 

 ovoid mass:s, from the smallest sizes to that of a hen's 

 egg, showing" the wnde prevalence of conditions favorable 

 to the operation of concretionary forces" (p. 61).^ These 

 gentlemen have without much doubt described the quartz 

 porphyry of the Moratock mine, or one similar thereto. 



It appears hig'hly probable that at least some of these 

 siliceous, so-called pebbly concretions are spherulites. 

 Whether they constitute Emmons' pebbly beds, from 

 which he determined the sedimentary orig-in of his Ta- 

 conic, is not known. However, it is quite possible that 

 the}' misled him in that direction. Certain it is that he 

 says: "I found, however, many beds among* them (slates 

 and associated rocks) which looked like sediments, were 

 porphyrized, and somewhat chang-ed, thoug-h not strictly 

 porphyries. I found after much search too, beds which 

 were unequivocally pebbly; and finally, to remove all 

 doubt, I was fortunate in discovering- that the porphy- 

 rized beds also frequently contained pebbles; proving- 

 most conclusively that they are sediments which were 

 partially altered" (p. 55). 



Thus he evidently mistook either the concretionary 

 form of the weathered porphyry and felsite, or else the 

 partially rounded felsite frag-ments in the accompanying" 

 pyroclastic breccias (which will be spoken of later on) for 

 pebbles. 



^Prof. Marsh in 18(>7 made a short study of E^mmons' 

 Paleotrochis, and in his words: "An examination of the 

 interior of several specimens clearly indicated that they 

 were not corals, and as soon as microscopical specimens 

 could be prepared, they were more carefully examined, 

 but no trace of organic structure could be detected, the 

 entire mass being- evidently a fine g-rained quartz. The 

 specimens examined were undoubtedly authentic examples 



lAm. Jour. Sei. (2), Vol. 45, 1868, p. 217. 



