NATURE OF PRESENT-DAY DEPOSITS 391 



California, describes an interesting deposit of gypsum with sulphur and 

 hydrocarbons, which is locally known as "The Oil Bubble." ^^ The 

 mound, which is 10 to 15 feet high and about 65 feet in diameter, is 

 composed of small crystals of gypsum, most of them less than one-quarter 

 inch in length, mixed with enough clay to jjermit the mass to be easily 

 kneaded. The mound also contained a small amount of material resem- 

 bling greatly oxidized asphalt stained slightly with native sulphur. At 

 the time it was visited the mound was wet and sticky and it is said to 

 remain moist throughout the summer. It is reported to give off bubbles 

 of gas; hence the name "bubble," the supposed asphalt suggesting the 

 name "oil." 



"The mound is formed by the evaporation of water carrying §;ypsum in solu- 

 tion, and clay probably being brought to the place by winds. The excessive 

 dryness of the surrounding country makes it seem probable that the water 

 comes from a considerable depth, rising through the Tertiary gypsiferous 



sandstones." 



The gypsum of Virginia is curiously banded with black streaks of 

 hydrocarbon, which entirely disappear when the gypsum is heated to 

 moderately high temperatures. At Stopinshof and Pawasser, in Eussia, 

 the gypsum beds are given a dark blue color by their bitumen content.^^ 



In the Aspy Bay district in Victoria County, Nova Scotia, the exposure 

 is described as "white and mottled white and gray, compact crystalliza- 

 tion showing some little anhydrite, which carries petroleum in small (pea 

 size) cells at the base of the exposures." ^^ The gypsum on the Geary 

 property, South Maitland, Hants County, Nova Scotia, is described as 

 containing "considerable anhydrite, and veins of dark carbonaceous and 

 reddish gypsum," ^* At Cheverie, in Hants County, Nova Scotia, the 

 rock in the Lown Head quarry is described as "carrying petroleum in 

 embedded cells, from which small quantities have been collected during 

 blasting operations." ^^ On Avon Eiver, Hants County, Nova Scotia, the 

 gypsum is described as of "a very fine white, compact variety, showing a 

 few streaks of black irregularly distributed through the white. The black 

 was high' in carbonate of magnesia and carried some bitumen and iron 

 pyrite." ^^ Within the town of Windsor, Nova Scotia, in the old Fellow 

 quarry, from which 500,000 tons of gypsum have been taken, anhydrite 



" U. S. Geol. Survey Bulletin 41.3, p. 15. 



1- Dammer u. Tletze : Die Nutzbaren Mineralein, II, p. 68. 



13 Cole : Gypsum in Canada. Canadian Dept. of Mines, p. 189. 



" Cole : Gypsum in Canada. Canadian Dept. of Mines, p. 214. 



1° Cole : Gypsum in Canada. Canadian Dept. of Mines, p. 218. 



" Cole : Gypsum in Canada. Canadian Dept. of Mines, p. 222. 



XXVIII — Bull. Geol. Soc. A.m., Vol. 32, 1920 



