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Show BERKELEY HILLS History of Stirring Geological ' Events Given in' Review i -at University. BERKELEY, Cal., Dec. 11. That a volcano once burst out in the Berkeley Hills has now been proved by the University of California. This volcano spilled molten rock all the way from Berkeley to a point five miles south of Hayward. Later a long succession of earthquakes took place, caused by shiftings of vast blocks in the earth's crusL Thus great rifts and fault were torn in this lava. bed. Then the water of storms and springs percolated through these earthquake fissures in the rocks and deposited a great variety of minerals. Such was the origin of Oakland's unusual mining industry the mining of pyriti- at Leona, as a material from which to make sulphuric acid. These stirring events in tho past geological history of the Berkeley Hills are told in a paper by Clifton W. Clark on "The Geology and Ore Deposits of the Leona Le-ona Rhyollte," recently issued in the University of California publication in geology. Clark points out that huge blocks in the earth's crust have slipped'ropeat-cdly slipped'ropeat-cdly along the Hayward fault, a line of cleavage between blocks of the earth's surface, running from Berkeley southeast along the base of the steep slopes of the Berkeley hills from the neighborhood of the Greek theater on the university campus at Berkeley on to Hamilton gulch, at the head of Dwight way, in Berkeley, where the extruded rhyollte the volcanic rock-first rock-first shows, on past tho Berkeley Institution Insti-tution for the Deaf and the Blind and the Claremonl hotel, on through a rift valley from Temescal lake to a point southeast of Leona Heights, then southerly; further on. up Arroyo Viejo creek, southeast through a saddle on the F. C. Talbot ranch, connecting with the oblique fault west of Luke Chabot, and on through several saddles sad-dles and breaks in tho western slope of the hills to the town of Hayward. Slippiugs of the earth's crust along this fault line still occur from time to lime. The rain water and spring waters wa-ters of countless centuries, percolating downward through the old lava deposit through fractures caused by slippings on tho earthquake fault, curried pyrlte downward and caused the deposit of considerable accumulations of this pyrlte. For a number of years mining has gone on and is continuing of such deposits of pyrito, near Leona Heights, cast of Oakland. The ore Is found in a fracture zone in ther hyolitc the volcano rock which is Joined and faulted so that considerable quantities of gouge and small displacements may be seen nearly everywhere in the mine, with abundant evidence of much intense fracturing that originally caused the localization of the ore body. Associated with tbc'pyrito are a number num-ber of other minerals, including chal-copyrite, chal-copyrite, copper, melanterlte, plsanile, chalcanthite, copiapite. epomitc, hematite, hem-atite, limonito, boothite, chnlcocite, bornite and sphalerite. None of these minerals in the Leona rhyolite except the pyrile is of any present economic importance. The oldest rockB in this region of the Berkeley hills, according tp Clark, arf .sandstones, basalts and other rooks . of . tho "Franciscan group." .AUo,y6uic3ev-Fraiiclscan'.' - deposits .are. several hundred foot of the Lower Cretaceous Cre-taceous or Knoxvllle formation, origin-Ally origin-Ally laid down far beneath the sea, ind then the Chlco Cretaceous, which represents a submarine deposit of " 1 " 1 - " 'nil. 1 ' - thousands of feet in depth of sandstones sand-stones and shales. A vast period of time then passed during which the hills were raised above tho sea and then most of these once submarine deposits washed away by erosion. iJ Then came the volcanic action which poured the Leona rhyollte for twenty miles along what is now the front of the Berkeley hills. |