proceedings: geological society 433 



that the oil-shale of the Green River formation is capable of yielding 

 more oil than the shale mined in Scotland, although the yield of am- 

 monia (principal byproduct) may be less than that derived from the 

 Scotch shales. Individual beds vary from place to place in thickness 

 and character, but the apparent persistence of the individual members 

 of the formation is remarkable. 



The beds of oil-shale were laid down in fresh water which had an 

 enormous expanse and was so deep that wave action had little effect on 

 the sediments. The richer beds of oil-shale contain an immense quan- 

 tity of vegetable matter, while the leaner beds contain much less. 

 Algae, mosses, ferns, pollen of higher plants, fungi, and anomalous 

 but well marked and characteristic forms of plant life are very common 

 in the rich shale, as shown in several hundred thin sections prepared by 

 Dr. C. A. Davis shortly before his death. Fish remains are in some 

 places present, insect larvae, fresh-water shells, , and even bird bones 

 have been found. 



It is believed that, at least in the Green River oil-shales, the oil is 

 indigenous to the shale, being formed from the vegetal remains in the 

 shale partly by the slow processes of nature, partly by the violent 

 destructive distillation in the laboratory. Dr. Davis in an unpublished 

 note says "the mineral (not organic) part of the rich bed is physically 

 so minute that if it were the sole original material into which the bitumi- 

 nous matter was injected the intrusion would have greatly distorted 

 the beds overlying the invaded ones, but no such distortion is observ- 

 able. . . . If, however, the bituminous matter is held in the partly 

 bitumified matter seen in an incompletely decomposed state in the 

 shale, heat might decompose the parent fossil material, and petroleum 

 in quantities proportionate to the percentages of plant remains might be 

 produced." 



Discussion: H. M. Ami spoke of extensive tests made by the Cana- 

 dian government on Nova Scotian shales. Near intrusives in these 

 shales some naturally distilled hydrocarbons have been found. The 

 occurrence of albertite was referred to. David White compared 

 albertite and gilsonite as to occurrence in fissures, and also compared 

 the lamination and algal growths in play a deposits with structures in 

 oil-shales. Winchester added that gilsonite veins seem to have 

 originated from oil-shales. They are found in the beds above and below 

 the shales. 



E. T. Wherry: Occurrence of calcite in silicified wood. A specimen 

 of silicified wood obtained from Yellowstone National Park and show- 

 ing calcite crystals scattered through its mass was described. The 

 calcites contain near their centers inclusions of well-preserved wood 

 cells, but outwardly are clear, except for a dark "phantom" line a short 

 distance from their, surfaces. The wood cell material crowded out by 

 the growth of the later portions of the crystals is heaped up as a dark 

 rim around them, no pressure effects being shown by the cells outside 

 of this rim. It is inferred that after the wood had rotted to the con- 

 sistency of a wet sponge the calcite started to grow from solutions 



