Notices respecting New Boohs. 



227 



with bones of extinct Mammalia, for instance Rhinoceros hesperius 

 and Mastodon americanns, have been met with in this gravel. 

 Flows of lava covered it ; and the glaciation of the Sierra followed, 

 leaving in ridges the lava-flows that had covered these old valley- 

 gravels, and making new valleys out of the intermediate rock- 

 margins of those gorges. Plate 7 represents the pestle and one 

 of the two mortars found, with stone spear-heads, by Mr. Neale 

 in 1870 ; and a woodcut shows a broken pestle found by Mr. Cla- 

 rence King in 1869. 



Dr. Becker gives some remarks on the correlation of the lavas 

 and gravels with the eastern deposits ; and proceeds to explain 

 that the great valley of California was formerly a Pleistocene gulf, 

 and the Pliocene animals may reasonably be supposed to have sur- 

 vived in the locality to a late period ; also that a local glaciation, 

 due to peculiar climatal conditions, may have occurred here after 

 the more general Glacial Epoch. 



At the reading of Dr. Becker's paper the Rev. G. P. Wright 

 gave some further information on the subject, to the effect that 

 another mortar had been found in the same gravel in 1887. 



Notes on the Early Cretaceous of California and Oregon. By George 

 P. Becker. Bullet. Geol. Soc. of America, vol. ii. 1891. 



The definition of this group and its fauna is detailed, showing that 

 the one group of strata in the Coast Ranges of California, called 

 the Knoxville group, and the other near Horsetown in Shasta 

 County, are probably equivalent to the Gault. In the Sierra 

 Nevada these strata are intersected by numerous auriferous quartz 

 veins ; in the Coast Ranges they are extensively metamorphosed 

 and yield quicksilver. 



The same group is represented at Riddles, Douglas County, 

 Oregon, and in Queen-Charlotte Islands. One of the leading 

 fossils is the Aucella, characterizing strata of approximately the 

 same age also in Alaska and British Columbia, and, according to 

 Dr. G. M. Dawson, even as far north as Porcupine River within 

 the Arctic Circle. Mr. J. S. Diller added the information that 

 both the Knoxville and the Horsetown beds are well exposed in 

 Tehama County, between the localities of California and Oregon 

 referred to by Dr. Becker. 



The Horsetown beds lie unconformably on nearly vertical slates, 

 and the disturbance thus indicated was probably Post-Triassic ; for 

 in the Mineral-King district, about two miles from the summit of 

 4he western branch of the Sierra, vertical slates associated with 

 eruptive granite contain casts of shells indicative of a Triassic 

 fauna. The author adds — " The main mass of the granite of the 

 Sierra is earlier than the Aacella-beds, and in part, at least, later 

 than these Triassic beds. It is very probable that a granitic extru- 

 sion accompanied the disturbance which led to the nonconformity 

 at Horsetown. In British Columbia Dr. Dawson has traced a 

 Post-Triassic upheaval, which was accompanied by granites. Thjs 



