Review of Recent Geological Literature. 117 
arras of sedimentation existed: (a) the Atlantic coast province, including 
various narrow seas bet ween the several pre-Cambrian ridges; (ft) a 
narrow sea extending along the western side of the Paleo-Appalachian 
range from the presenl site of Labrador to Alabama: (c) a broader sea 
on the western side of the continent, west of the eastern Paleo-Rocky 
mountain ranges, that extended from thesouthern portion of the presenl 
site of Nevada northward into British Columbia and probably toward the 
Arctic circle, and south to the Paleo-Gulf of Mexico and thus connect- 
ing with the Paleo-Appalachian sea. 6. Sedimentation probably began 
in the Paleo-Appalachian and Paleo-Rocky Mountain seas before Cam- 
brian time, and it continued without any known unconformity to the 
close of Lower Silurian (Ordovician) time in the northern Paleo-Appa- 
lachian sea, and with relatively little interruption to the close of Paleo- 
zoic time in the Paleo-Appalachian sea south of New York, and in the 
Paleo-Rocky Mountain sea. 7. The Cambrian sea began to invade the 
great Interior Continental area in Middle Cambrian time, and extended 
far to the north toward the close of the period. 8. The depression of 
the continent in relation to sea level began in [ire-Cambrian time and 
continued with a few interruptions until the close of Paleozoic time. '.». 
The relative positions of the continental area and the deep seas have not 
changed since Algonkian time. 10. The sediments of Cambrian time 
were accumulated to a great extent in approximately shallow seas, ex- 
cept in portions of the Paleo-Kock\ Mountain and Paleo-Appalachian 
seas. 11. The Lower Cambrian fauna lived in the seas of the Atlantic 
coast province, the Paleo-Appalachian and the Paleo-Rocky Mountain 
seas. 12. The Middle Cambrian fauna of the Atlantic basin is not 
known to have penetrated into the Paleo-Appalachian or Paleo-Rocky 
Mountain seas, except in the case of a few species now found in Ala- 
bama anil probably eastern New York. The portion of the fauna occu- 
pying the same relative st rat igraphic position in the group is essentially 
the same in the Paleo-Appalachian and Paleo-Rocky Mountain sections. 
13. The Upper Cambrian fauna was distributed over the broad Interior 
Continental area and in the Paleo-Appalachian and Paleo-Rockj Moun- 
tain seas, but it has not been recognized by the same genera and species 
in the At hint ic coast province, the fauna of the latter being more closely 
allied to that of the Upper Cambrian of the eastern side of the Atlantic 
basin. \\ . i . 
The Eruptivi Rocks, of Electric Peak and Sepulchn Mountain, Yellow- 
stone National Park. By Joseph Paxson [ddings. Pages 569-664; plates 
xlvi-liii, and figures 79-81. (Accompanying the Twelfth Annual Re- 
port, U. s. Geol. Survey.) The study of the chemical composition of 
the intrusive rocks of Electric peak and of the volcanic rocks of Sepul- 
chre mountain proves thai these two groups of rocks have identical 
chemical compositions. The varieties that have been analyzed are 
mineralogical and structural modifications assumed bj the magmas on 
cooling, and the analyses serve as indications of the range of their 
chemical variability. From the geological structure of the region, the 
