116 The American Geologist. August, 1894 
region and from the Mississippi basin, spreading gravel, sand, and loam 
over the coastal plain and along the greal valley during the early pari 
of a time of continental elevation. The land had lain during the long 
Terl ian periods al lower altitudes, and itssurface was largelj enveloped 
by residual clays and by alluvial sand and gravel. With the elevation 
of the continent, increased rainfall and snowfall and resulting river 
Hoods swepl away these superficial materials from the higher lands and 
spread them on the coastal plain and along the Mississippi valley, where 
the streams expanded over broad areas with shallow and slackened cur- 
rents. As the elevation increased, however, the rivers would attain 
steep slopes and finally erode much of the deposits which they had pre- 
viously made. During the culmination of the uplift, which the re- 
viewer thinks to have produced the northern ice-sheet. Chesapeake and 
Delaware hays were excavated and erosion was in progressal a far more 
rapid rate than with the present low altitude of this region. Prof. E. 
W. Hilgard, by whom the formation was first studied and named, be- 
lieves that during Lafayette time the Mississippi valley had a greater 
descent and stronger currents of its river floods, the increased altitude 
of the interior of the continent having been apparently 4,000 to 5,000 
feet, sufficing probably, in its culmination, to bring the cold climate 
and ice accumulation of the Glacial period. According to this view the 
Lafayette period may be considered, as by Hilgard, spencer, and Smith, 
to be early Quaternary or Pleistocene, representing the initiation of the 
conditions which resulted in the Ice aire. w. r. 
Tin North American Continent during Cambrian '/'inn. Ii\ Charles D. 
WaIiQOTt. Pages 523-568; plates xlii-xlt, and figures 73-78. (Accom- 
panying the Twelfth Annual Report. I". s. Geoh Survey.) The conclu- 
sions reached in this paper are stated by the author as follows: 1. The 
pre-Cambrian Algonkian continent was formed of the crystalline rocks 
of the Archean nuclei, and broad areas of superjacent Algonkian rocks 
that were more or less disturbed and extensively eroded in pre-Cambrian 
time, lis area was larger than at any succeeding epoch until Mesozoic 
time. 2. ()n the east the Paleo-Appalachian system of mountains was 
outlined by a high and broad range, or system of ranges, that extended 
from the present site of Alabama to Canada, and subparallel ranges that 
formed the margin of seas and straits to the east and northeast of the 
northern Paleo-Appalachians or the Paleo-Green mountains anil their 
northeastern extension toward the pre-Cambrian shore line of Labrador. 
.'I. On the Pacific side the eastern mass of the Paleo-Rocky mountains 
formed a broad mountain barrier that extended from the present region 
of Arizona and New Mexico to Montana, and toward the Arctic circle. 
upon the western side of an interior land area. To the west the primi- 
tive Sierra Nevada protected the Nevada sea and extended far to the 
north. I. The interior continental area was. at the beginning of Cam- 
brian time, an elevated, broad, relatively level plateau between the 
Paleo-Appalachian sea on the east and the Paleo-Rockj mountain bar- 
rier on the west. .">. At the beginning of Cambrian time three principal 
