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DETRITIC FORMATIONS 87 
the continental strata on) the Nevado de Famatina, mentioned by 
_ Stelzner and Bodenbender (see the page 59). 
The Pagancillo lowland and the Vinchina valley. 
About the stratigraphy of the vast, sunk area of the Pagancillo 
lowland I have made but few personal observations. According to 
Bodenbender (1911) the whole interior of this area is occupied 
_ by tertiary strata, lying over a basement of cretaceous sandstone, 
outcropping along the borders of the depression, where upbending 
phenomena are seen. Also to the] north, in; the bottom of the 
~ Vinchina valley, the cretaceous strata are exposed. 
Good profiles can be studied along the course of the Rio Ber- 
mejo to the south from Maldonado and especially in the traversing 
- quebrada of the Paso de Lamar. This water gap crosses the sand- 
stone ridge, which forms the southern (southeastern) prolongation 
of the Cerro Bola and is known as the Lomas Coloradas with their 
highest point, the Cerro Colorado. To the south of the paso there 
rises another mountain, the Cerro Rajado, the northern head of a 
long sandstone cuesta, the Sierra del Valle Fertil. | 
The profile in the Paso de Lamar begins in the west with pale 
greenish sandstone layers with numerous basic sills, according to 
Bodenbender (1911) of rhaetic age. The strata dip toward the 
east, but many irregularities may be observed, as flexures and a 
local döme-shaped uplift. Red sandstones of considerable thick- 
ness changing upward into brown layers, lie with a complete con- 
formity upon the rhaetic strata. These strata are considered by 
Bodenbender (1911) as of cretaceous (and jurassic?) age. The 
Rio Bermejo; upward, out of the paso, in the direction of Maldo- 
nado, the brown-red sandstone forms the whole underground, always 
dipping under the same angle to the east, soon covered with the 
old gravel sheets of the Pagancillo lowland. In the vicinity of the 
river bed the sandstone is well exposed, partly as isolated erosion 
remnants of peculiar shape. The slope of the Cerro Colorado to 
