HOT WATER SUPPLY OF THE HOT SPRINGS 437 



of springs active or formerly active lie on the sandstone or on the 

 immediately adjacent Stanley shale. 



The Hot Springs sandstone of this body is somewhat harder 

 than normal, is a darker color, and is much fractured. These 

 fractures are commonly sealed with quartz and calcite, both appar- 

 ently deposited by the hot waters. In a number of instances, 

 notably in the Maurice and "new" bathhouses, where excavation 

 has exposed the sandstone, the hot water can be seen emerging 

 from the cracks and fissures of the rock. 



The fractured sandstone is then the conduit for the hot water 

 which is prevented from breaking out in the lower depression 

 (the creek bed) by the Stanley shale through which it maintains only 

 a few openings. Similarly the water closes the cracks and joints 

 of the sandstone by deposition and consequently all the springs 

 do not break out at the contact of the sandstone and Stanley shale 

 but many of them emerge higher up the hill. 



On the hillside, back of the bathhouses, the outcrops of sand- 

 stone are each extended in a northeasterly direction. Each outcrop 

 in addition is marked by strong, nearly vertical jointing in this 

 direction. The maps show also that the spring openings are 

 arranged in lines of which the most marked is that belt of springs 

 from the Egg Spring, No. i, to the Maurice Bathhouse, which 

 includes the strongest springs of the group. Four such lines of 

 springs are marked on the map. These lines are approximately 

 parallel to the thrust fault, postulated between the east and west 

 bodies of the Hot Springs sandstone. A fifth line may be drawn 

 parallel to the contact of the sandstone with the shale, but this 

 line includes many springs situated on other lines. Obviously, if 

 the sandstone were uniformly permeable and the shale uniformly 

 impermeable, all the springs would lie on the contact. 



The strong jointing in the sandstone, and the distribution and 

 elongation of outcrops indicate a fracturing of the sandstone in a 

 direction north northeast parallel to the Hot Springs anticline. 

 Weed^ noted the Kne of springs extending from Egg Spring, No. i, 

 to the Maurice Bathhouse and suggested that this line was a 

 "fault fissure." It seems more likely that this line and the three 



' Op. cit., p. 201. 



