418 
STRATIGRAPHICAL GEOLOGY 
denbender, Stappenbeck, and Stelzner. Keidel devotes his notes to 
the region lying between the Rio Jachal and the Rio San Juan. 
He carries out a minute study of the sediments as to coloration, 
mega- and microstructure, weathering, and fossil content, giving 
a number of sections to show the succession of sediments in the 
region of Cerro del Fuerte, to the east of Jachal, through the 
Cerro del Agua Negra, a little to the south, and through the 
Sierra de Talacasto, still farther to the south. In the Talacasto 
region he finds a change in the character of the sediments. Here 
a sequence of unfossiliferous grauwacke, sands, and shales, with 
glacial deposits above rests in some places on Siluric and in others 
on Early Devonic strata. These sediments were formerly consid¬ 
ered Devonic in age despite the fact that the more northern true 
Devonic beds are abundantly fossiliferous, and for this reason he 
is inclined to believe that they are probably sediments of Mid to 
Late Carbonic age. This may be considered unproven. 
The structure of the area is complicated, and offers a field for 
considerable study since comparatively little work has been done 
on the geology of the region. It appears, however, from the ob¬ 
servations carried out that the region was formed by a strong 
pressure directed toward the east, folding and fracturing the older 
Paleozoic sediments and thus forming the Precordilleran struc- 
R. Lke Collins. 
Stratigraphic Sequence of Southern Patagonia. The De¬ 
cember (1921) number of the Geologische Rundschau con¬ 
tains an interesting contribution to the geological literature of 
Patagonia, by A. Windhausen. The author presents some new 
observations and conclusions on Late Cretacic stratigraphy, and 
general structural elements; at the same time he takes the oppor¬ 
tunity to review the results of Stappenbeck, Keidel, and others 
who have worked in the region. 
The Late Cretacic section is divided into two principal forma¬ 
tions, a lower Variegated sandstone, and, conformably above it, 
the Dinosaur beds. Both are mainly of continental origin, and 
both contain a marine transgression near their upper limits. The 
Areniscas Abigarradas beds are composed of several hundred 
meters of compact brown and yellow sandstones which outcrop 
over a wide area in the territories of Rio Negro, Nequem, an^i 
elsewhere. Above this formation there are 200 to 250 meters of 
