70 The American Geologist. February, i8n» 
to their junction with the S?»ierra Nevada, yet there seems to be no 
doubt that such is actually the fact, as was found to be the case 
with the northern Coast ranges. 
In my former paper I traced the Palaeozoic rocks of Shasta 
county, part Carboniferous and part probabl}' Devonian, south 
along the main Coast range to San Francisco ))ay. The litho- 
logical features of the series were quite constant the whole dis- 
tance, sandstone, slate and banded jasper predominating. The 
effects of intense dynamical action, resulting in crushed and 
contorted strata; and secondary silicification, in which these 
strata were filled with a net-work of minute quartz veins, were 
seen to be constant and distinguishing features. With the ex- 
ception of fossils of probable Palseozoic age from western 
Tehama county, none were found in this older series; but the 
Knoxville, the lowest known Ci'etaceous in the state, wherever 
present, was found generally to contain Aucella, and to rest 
totally unaltered and unconformable on the ]VIetamorphic series. 
The bay of San Francisco is formed by a depression extending 
across the Coast ranges from the great interior valle}' to the 
ocean. The outlet to the bay, the Grolden Gate, is bordered by 
sandstone and jasper containing dikes of serpentine and other 
greatly altered eruptives. As we go southward the ranges form- 
ing the Coast system become very regular in their northwest and 
southeast trend. They do not run quite parallel to the coast, but 
lap past each other, forming a succession of headlands. Between 
these are long narrow valleys opening northwestward. 
The three most prominent ranges are the Monte Diablo, the 
Santa Cruz and its southern prolongation the Gavilan, and the 
Santa Lucia. They consist chiefly of granite, crystalline schists, 
and often but slightly altered sandstone, slate and jasper. As 
has been noted before, these rocks are so crushed that no system 
of folds can be made out, and the strike and dip are often almost 
indistinguishable. Greatly decomposed eruptives of many varie- 
ties are abundant. No granitic rocks have been found in the 
Monte Diablo range, but mica, hornblende and glaucophane 
schists appear in places. The first known outcrop of granite in 
the Coast ranges south of Trinity count}', is on Tomales point, 
about twenty miles northwest of San Francisco. This outcrop 
lies in line with the granitic rocks of the Santa Cruz mountains, 
and is quite likely a continuation of them. South of San Fran- 
