2G4 The American Geologist. April, 1891 
The chief general interest of the volume centers in Prof. Salisbury's 
discussion of the age of the strata of the ridge. The ridge itself is one 
of those remnants from erosion left by the Mississippi river which are 
found frequently along the course of the valley in its non-glaciated por- 
tions. It extends from near Cape Girardeau, in Missouri, to Helena, in 
Arkansas, making, in its central portions, a broadly crescentic bend to- 
ward the west. 
Prof. Salisbury regards the superficial loess and loam mantle of the 
ridge as referable clearly to the Pleistocene, "and under the Pleistocene 
to the first glacial epoch," and he is of the opinion that the second 
glacial epoch has no representative in the ridge. The river-terraces that 
characterize that epoch by heading in its terminal moraines pass below 
the alluvium of the Mississippi before reaching the latitude of Crowley's 
ridge. The most southern point at which such have been recognized in 
the Mississippi valley, being a short distance above Cape Girardeau, 
where a remnant exists in a tributary valley. 
The gravels and sands of Crowley's ridge are unconformable below 
the loess, and are frequently separated from the loess by a layer that ex- 
hibits a characteristic humus, showing the interposition of an epoch of 
subaerial exposure. This humus bed he considers the dividing line be- 
tween the Pleistocene and Pre-pleistocene. The gravel and sand of the 
body of the ridge therefore he regards as not of glacial origin — and this 
conclusion he extends to large areas in western Tennessee and Ken- 
tucky and in southern Illinois, and in eastern Missouri where such 
gravels and sands extend, and where they have sometimes been reported 
as of glacial origin. This important conclusion is well sustained by the 
handling of the facts and can hardly be questioned. The paper points 
to a delimitation of the Pleistocene from any underlying older but sim- 
ilar formation, and mentions the characters by which the distinction 
may be made by any geologist, and therein it adds an important advance 
step to our knowledge of the Pleistocene. 
LIST OF RECENT PUBLICATIONS. 
1. State and Government Reports. 
Bulletin No. 2, Geol. Surv. of Mo. A Bibliography of the geology of 
Missouri. F. A. Samson. 
Bulletin No. 3, Geol. Surv. of Missouri. The clay, stone, lime and 
sand industries of St. Louis city and county, G. E. Ladd ; The mineral 
waters of Henry, St. Clair, Johnson, and Benton counties, A. E. 
"Woodward. 
Bulletin No. 4, Geol. Surv. of Missouri. A Description of some 
Lower Carboniferous crinoids from Missouri, S. A. Miller. 
Report on the Cahaba coal fields. Joseph Squire ; Geology of the val- 
ley regions adjacent to the Cahaba field, E. A. Smith ; Geol. Surv. of 
Alabama. 31 Figs., 7 plates and large map. 
