756 



SCIENCE. 



[N. S. Vol. XIV. No. 359. 



Ordinarily it will enter the upper part 

 while it is still descending ; it Avill enter 

 the central part laterally ; it will have be- 

 gun its ascent before it enters the lower 

 part. Therefore, a fissure upon the middle 

 of a slope will be very likely to receive wa- 

 ter from above, from the side and from be- 

 low. Bat at a certain area of a fissure well 

 up on the slope the water continuously re- 

 ceived at the upper side of the fissure will 

 escape laterally at the lower side. This 

 water and that entering the ground below 

 the upper fissure will make its way to the 

 fissure below the valley. But here the level 

 of ground water is at the surface. Conse- 

 quently all the water entering this fissure 

 will ascend quite to the surface, and issue 

 as a spring. If there be a fissure at the 

 crest we can see that the descending water 

 will go a long way down ; but the waters 

 will nowhere be ascending. If there be a 

 fissure on the slope, both descending and 

 ascending waters will ordinarily be active ; 

 although it is of course recognized that in 

 fissures thus located the conditions may be 

 such that the waters will ascend or descend 

 only. If there be a fissure below a valley 

 where the level of ground water is at the 

 surface the water will all be ascending; and 

 there will be no descending water. At 

 such places we have springs. Springs do 

 not issue from the tops of mountains, but 

 from slopes and valleys, most frequently 

 the latter. Illustrating this are the Yel- 

 lowstone Park springs of the Firehole River. 

 The waters which feed the springs fall upon 

 the crests and slopes of the mountains ad- 

 jacent ; on their way to the valley go deep 

 below the surface, and at the Firehole as- 

 cend as hot springs and geysers. The water 

 is driven by gravity due to a considerable 

 head and the lower temperature of the de- 

 scending column. 



You are all doubtless aware that three 

 theories are maintained as to the course of 

 the waters which deposit ores. Some hold 



that the waters doing the work are descend- 

 ing ; others that they are laterally moving ; 

 others that they are ascending. The first is 

 known as the descension, the second as the 

 lateral-secretion, and the third as the ascen- 

 sion theory. If my argument be correct as to 

 a limit to the zone of fracture, fissures, as 

 well as all other openings, must gradually 

 become smaller and smaller, and finally die 

 out altogether. Water in a fissure may de- 

 scend or may ascend for a considerable 

 distance ; but it is perfectly clear that, so 

 far as fissures are concerned, except for the 

 small amount entering the surface openings, 

 the water must enter laterally. Conse- 

 quently, if we apply the lateral -secretion 

 theory broadly enough, we may say that all 

 the waters which feed the fissures are 

 lateral-secreting waters. But if we are de- 

 scension ists, and consider only the upper 

 part of a fissure on the slope — and that is 

 what many very naturally have done, be- 

 cause this is the part of the fissure most 

 easily observed — we may say that the 

 waters which are doing the work are de- 

 scending waters. Or, if we are in such a 

 district as that of the Comstock lode, in 

 which are found great volumes of ascending 

 water, we may say that the waters which 

 are depositing the ores are ascending. All 

 may be correct. But in the past Sandberger 

 held that lateral-secreting waters in the 

 narrowest sense did all the work, and he 

 refused to believe that ascending and de- 

 scending waters were of importance ; and 

 Posepny held that ascending waters did 

 nearly all the work, and gave small con- 

 sideration to the lateral-secreting and de- 

 scending waters; whereas you see with 

 perfect clearness that each theory is in- 

 complete. All are needed ; they supple- 

 ment one another. 



The next point to consider is why the 

 metals are precipitated in veins. The 

 salts of the valuable metals may come 

 from any of the places visited by the oc- 



