The Ohio ^Njaturalist, 
PUBLISHED BY 
The Biological Club of the Ohio State University. 
LIBRARY 
NEW YORI 
BOTANICAL 111 1 
GARJDBN. ' 
Volume XI. 
FEBRUARY. 1911. 
No. 4. 
TABLE OF CONTENTS. 
Stauffer— A Review o£ Literature on the Geology of South America 273 
Selby — The Blister Rust of White Pine (Peridermium Strobi Klebahn) Found in Ohio 285 
Griggs — Eupatorium Rotundifolium in Ohio 287 
Wells— M eetings of the Biological Club 287 
A REVIEW OF LITERATURE ON THE GEOLOGY OF 
SOUTH AMERICA. 
C. R. Stauffer. 
ARCHEOZOIC AND PROTEROZOIC (PRE-CAMBRIAN) 
The pre-Cambrian of South America is mainly limited to 
three regions: 
(a) Guiana, including portions of northern Brazil and 
southern Venezuela. 
(b) The highlands of eastern and southern Brazil. 
(c) Narrow strips in the Andes lying north of 40° S. latitude, 
together with similar strips running north and east from the 
main chain in northern Venezuela. These Andean strips may be 
of much later age, but they have been referred to the pre-Cambrian. 
The first of these regions includes an area of more than 500,000 
square miles of elevated broken land. It is separated from the 
Atlantic coast by a 10 to 70 mile wide strip of post-Tertiary sands 
and gravels, is (according to Crosby) bordered on the north and 
west for a distance of 800 miles by the Orinoco River, and to the 
south dips under Paleozoic and more recent sediments along a 
line which Derby draws approximately “from the mouth of the 
Amazonas, in latitude 1° N., to the confluence of the Rio Negra 
and Rio Brancho, between 1° and 2° S. latitude.” 1 
The rocks of this region Crosby has grouped together in 
somewhat the following manner: 
Pre-Cambrian 
(4) Semi-crystalline schists and marbles. 
Great unconformity 
(3) Montalban series. Gneisses and schists cut by coarse granite 
dikes. Garnets common. 
(2) Huronian series. Quartz porphyry and felsite associated with 
various hornblende and slaty rocks showing distinct 
bedding. 
(1) Laurentian series (?). Granite and some syenite. 2 
1. Crosby, W. O., Proc. Boston Soc. Nat. Hist., Vol. XX, 1881, p. 484. 
2. Crosby, W. O., Loc. cit., p. 493. 
