244 The American Geologist. April, 1894 
Alu yum. 
There are gravels and fine sediments in all the valleys and 
along the rivers, that have been formed in the Recent period. 
The Upheavals recorded in the Rocks of the Sierra 
Nevada. 
Pre-Carboniferous land urea. In the portions of the range 
studied by the writer, comprising a strip thirty miles wide, 
extending across the mountains just south of the fortieth 
parallel, and a large part of the range to the south of Placer- 
ville in Eldorad untv. the first record of a land area is that 
furnished by a bed of conglomerate in the foot-hills of Cala- 
veras and Amador counties. This conglomerate is interstrat- 
ified with slates and limestone, the latter containing Fusulina 
cylindrica and rounded crinoid stems, indicating the Carbon- 
iferous period. At one point in Calaveras county this con- 
glomerate is within twenty feet of the limestone croppings. 
all the rocks having the same strike and dip. No fossils were 
found in the conglomerate itself, and therefore the possibility 
remains of its being of later age and folded in with the Car- 
boniferous sediments. 
This conglomerate contains pebbles of diabase, hornblende- 
porphyrite and quartzite, the igneous pebbles being much the 
most abundant. The conglomerate is well exposed in a field 
three miles northwest of Golden Gate hill (Nos. 22 and 56- 
59, Calaveras county collection), and west and northwest of 
Sugar Loaf (Nos. 30 and 31. Amador county collection), the 
last conglomerate stratum being to the east of the Willow 
Springs serpentine belt. 
h is possible that the qitartzite of Mi. Aigare and other similar 
masses in the southwest portion of the Placerville atlas sheel represent 
remnants of ihis hypothetical pre-Carboniferous land area. These 
quartzite masses have a somewhat irregular strike and dip, and in this 
respect vary from the Carboniferous bell lying to the east of Mt. Aigare, 
the rocks of which dip al a high angle and strike nearlj north and 
si hi t li with great regularity. These quartzite areas, arc. however, rep- 
resented on the Placerville geological sheel as of the Calaveras forma- 
tion, there being no positive evidence in the contrary. 
Another conglomerate bed thai is. perhaps, of Carboniferous age is 
exposed by the road to Cherokee to the south of Monte de Oro on the 
Chico alias sheei. This contains pebbles (No. 1 l!» Butte countj*) of tine 
grained siliceous rocks and of porphyrite. The black slate associated 
