Arizona weekly journal-miner., 1901-04-17
GEOLOGY OF PETROLEUM.
Prof. Theodore B. Comstock Talks of it to The Los Angeles Academy
 of Science.

Prof. T. B. Comstock the vel
 known mining man and scientist
 gave a very inte1esting talk recently
 on the Geology of Petroleum" be-
 fore the Los Angeles Academy of
 Sciences, a synopsis of which togeth-
 CT with very fine portrait of Profes-
 sor Comstock is produced in the Los
 Angeles Herald of Saturday. He said:
 Until within the last ten or twenty years it has not been considered that oil was to be found in any quantity in any of the recent rocks. The chem ists who first studied petroleum thought that it was a product of dis tillation from vegetable products, and that that distillation necessarily i'm piled that it was in the lower rocks where it was subjected to great pres sure for the generation of heat, and that the same properties that devel- oped oil in the more recent rocks.
 "With the finding of oil in Califor- mia and other portions of the world in the recent rocks a new theory arose, to the effect that in the oil of these fields there is more animal than veg table in the material from which oil was distilled by nature, and in some places, notably the Green river, Wyo- ming, oil is found in great beds of fossilized fish, fact which gives color to the theory.
 'In the early days of the oil indus try it was believed that the Trenton rocks were the home of oil, though later in Colorado and Russia oil was found in cretaceous, and in California in the tertiary formations.
 Ut is point of greatest interest to geologists that so many products of petroleum under different treatments are found, while so few of them are found in nature. Oscillation of pe- troleum under different temperatures and under different conditions has brought out a vast number of pro- ducts of great value"
 The speaker entered into a descrip- ton of anticlinals, synclinals and an ticlinal valleys, using several articles which lay before him to illustrate his points. He said that anticlinals and synclinals were matters of structure, and not of topography. An anticli nal is an upward fold of strata, syn clinals is the downward fold, and an anticlinal valley is depression where an anticline once existed, but which has been carried away by the ele- ments, leaving a depression in its place. Many of the highest peaks are the bottoms of old valleys, while the former hills have been carried away from where the valleys are now situated. If oil and water are in an anticlinal, the oil will tend to rise to the surface, and generally the best place to drill is on the apex of the an ticlinal. If the gas pressure is great the oil may come out in the form of a gusher, and the life of the well will depend on the area of gas bear ing rock tributary to the well.
 He says that if in nature we can find the conditions which exist in laboratory, we may find various quail ties of oil at different depths, the oils forming in layers according to their specific gravity.
 He thought that a knowledge of the geology of the state was highly de- sirable, illustrating the fact with ex- periences of drillers from other oil fields, who are governed to great | extent by their individual experiences and without knowledge of what to expect in this country of different condition.
 The speaker illustrated the possi- bility of oil finding its way, even for miles, through faults in the rocks, and developing seepages a long distance from the real deposits, thus tending to confuse drillers, who expect to 1 make big strikes in the immediate vicinity of a seepage. He declared that oil might or might not be found | in the immediate vicinity of an oil seepage, but that generally it was safest to get as near as possible to the apex as an anticlinal. Sometimes oil is found on one side, and in other places on both sides of an anticlinal, according as the formation may dis pose of the flow of oil through the porous rock which carries it.
 But even with a knowledge of geol- ogy, the speaker said that men were all at sea through their inability to peer into the earth, until a drill had penetrated the earth and brought forth knowledge of the conditions which exist under ground, while there is nothing by which to determine with any degree of certainty the pres ence of oil under any given spot.