190~ 



SOmNGE. 



[N. S. Vol. V. No. 109. 



that this has proved to be one of Dr. Coues's 

 happy intuitions, and that his nomen nudum only 

 awaits a description to talce a secure place in 

 ornithological nomenclature. 



Dr. Emil Holub's brilliant description of a 

 winter roosting place of Sirundo rustica must 

 not pass unnoticed, nor must Mr. J. A. Allen's 

 article on 'the migration of birds.' The latter 

 is an exposition of the subject excellently suited 

 to the unscientific reader, for whom, doubtless, 

 it was intended, but it contains one or two 

 statements that the field ornithologist of large 

 experience might not assent to. Among the 

 rest of the papers there are some, of which there 

 is nothing especial to be said ; others might bet- 

 ter never have been written. 



C. F. Batcheldek. 



SCIENTIFIC JOURNALS. 



JOURNAL OF GEOLOGY, NOVEMBEE-DECEM- 

 EEE, 1896. 



Age of the Auriferous gravels of the Sierra 

 Nevada : By Waldemar Lindgeen ; with a Re- 

 port on the flora of Independence Hill : By F. H. 

 Knowlton. An attempt is made to definitely 

 fix the age of the auriferous detrital rocks of the 

 Sierra Nevada, resting uncomformably upon the 

 bed rocks at high elevations and covered by 

 volcanic flows. The beds include the deep 

 gravels, the bench gravels, rhyolitic tuffs, 

 gravels of the rhyolitic period, gravels of 

 the inter-volcanic erosion period and ande- 

 sitic tuffs and tufFaceous breccias. No fossils 

 have been found in the deep gravels. They 

 are older than the bench gravels, and may be 

 as old as the Eocene. At Independence Hill 

 leaves occur in a whitish or bluish clay inter- 

 bedded with the uppermost gravels of the ante- 

 volcanic period. These plant forms point very 

 clearly to the Miocene age of the deposit. The 

 lone formation, correlated with the bench grav- 

 els, is also shown to be Miocene by the presence 

 of characteristic shells. These gravels are prob- 

 ably Upper Miocene. The gravels of the inter- 

 volcanic period and the andesitic tuffs are prob- 

 ably Lower Pliocene or Upper Miocene. In 

 early Cretaceous the Mariposa and earlier beds 

 were folded and eruptions were continued from 

 the Jurassic. Shortly before the Chico the 



Sierra Nevada became separated from the Great 

 Basin. In Chico time the sea advanced east- 

 ward. In late Chico and Tejon time the 

 Sierra Nevada was being eroded, the greater 

 part of the Chico sandstone being cut away. 

 In early Miocene the sea retreated westward. 

 The Sierra assumed the topography since pre- 

 served. The relation of the two eroded sur- 

 faces. Cretaceous and Miocene, is clearly dis- 

 cernible from the lower foot hills. In late Mio- 

 cene (lone) the sea moved eastward and gravels 

 were formed. The gravel period was closed by 

 rhyolitic and andesitic eruptions with Pliocene 

 elevation. The andesitic flows are supposed to 

 mark the close of the Pliocene. The Pleisto- 

 cene was a period of erosion, with minor basaltic 

 eruptions in the earlier and middle portions, and 

 glaciation later. 



Anorthosites of the Bainy'Lahe Region : By A. 

 P. Coleman. Lawson has described eruptive 

 masses through the Keewatin of the Rainy Lake 

 region. The basic eruptions were identified 

 as anorthosites, the larger area enclosing the 

 southern arm of Bad Vermilion Lake. The 

 rock presents some differences from typical 

 anorthosites, an analysis showing that it is one 

 of the most basic rocks. Lawson thought the 

 area represented the truncated base of a Kee- 

 watin volcano. In this he was probably not 

 correct, as apparently a long interval separated 

 the anorthosite eruption from that of the 

 granite. 



Mechanic of Glaciers I: By Haeey Field- 

 ing Reid. The greatest flow occurs through a 

 section at the n6ve line, and diminishes as we go 

 up or down the glacier from here ; the diminu- 

 tion increasing with the distance from the n6v6 

 line. In glaciers with beds of uniform slope the 

 velocity and flow increase and decrease to- 

 gether, though not in the same proportion. 

 In a glacier of indefinite length and uniform 

 section the direction of the flow would be par- 

 allel to the slope, and the velocity parallel with 

 the axis would not vary along the direction of 

 flow. The velocity of a point under such cir- 

 cumstances would be the normal velocity cor- 

 responding to that form and size of cross-section. 

 A glacier of uniform section could not exist if 

 there was any melting ; the slope of the glacier 

 being uniform, wherever there is melting, the 



