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University of California. 



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series. 2. They are probably later than the Monterey series. 3. 

 They are older than the newer terrace formations, which mantle the 

 lower slopes of the coast. 



When we come to the San Jose area, however, evidence is pre- 

 sented which enables us to locate with great precision the relative 

 age of the eruption. Here we find a sheet of carmeloite lava, amyg- 

 daloidal in places, and about 60 feet thick, intercalated with the 

 terrace formations, conforming to their attitude and clearly contem- 

 poraneous in origin. The gravels and conglomerate here represent 

 an ancient delta of San Jose Creek when the land was several hun- 

 dred feet lower than at present; when the delta was partially built up 

 to the dimensions which it eventually attained, the lava was poured 

 out over its surface, and was then buried by subsequent accumula- 

 tions. The portion of the lava sheet now revealed mantled the 

 outer edge of the delta surface where it began to pitch steeply into 

 deep water, and the lava flowed over this steeply sloping edge of 

 the accumulating gravel. Thus the age of the carmeloite lava is 

 definitely located as contemporaneous with that stage of the delta- 

 forming depression at which the land had reached an altitude of 400 

 to 500 feet lower than at present. The lavas which flowed over lower 

 slopes and were mantled by the terrace gravels of successive stages 

 of the subsequent uplift, were, therefore, submarine flows, a fact 

 which may in future prove of much interest petrologically, in com- 

 parisons of subaerial and submarine lavas. 



THE ANCIENT BASE-LEVELS OF THE COAST. 



Ancient Ocean Strands. — The abundant evidences of the former 

 occupation by the sea of the coastal slopes of Carmelo Bay are 

 among the most interesting and attractive features of the geology 

 of the region. Up to elevations of at least 800 feet above the pres- 

 ent sea level there may be observed various distinct strands of the 

 ocean in the form of terraces, a beach, a delta, sea-cliffs with Pholas 

 borings and marine formations of sand, clay, sandstone, incoherent 

 beach pebbles, and compact, cemented conglomerates. The terraces 

 are not confined to the coastal slope, but extend up the valley of 

 the Carmelo River for many miles. These may be seen to advan- 

 tage from the sand bar at the mouth of the river in an early morn- 



