480 H. J. Biddle — Surface Geology of Southern Oregon. 



effected did the outflowing waters have sufficient fall to carry 

 on the work of erosion. Of course the hypothesis is admissi- 

 ble that the lake had at first no outlet, and was in course of 

 time tapped by a stream belonging to another drainage system, 

 cutting back its channel across the divide. Had the climatic 

 conditions of a former period continued to the present day, the 

 work of deepening the channel of outflow would most likely 

 have gone so far as to completely drain the valley, and leave 

 only marshes and meadows in place of the present water body. 

 But before this task was accomplished the supply of water was 

 so diminished that the lake disposed of it all by evaporation, 

 and none escaped to continue the cutting down of the outlet. 



The question naturally occurs, did the great lake north of 

 this also cut down its outlet ? But as there is no evidence of 

 erosion by running water in the pass mentioned, which was 

 once a strait connecting the two water bodies, the question 

 must be answered in the negative. Naturally nothing could 

 be accomplished toward deepening this channel until the level 

 of Goose Lake had been lowered to about the level of the bot- 

 tom of the strait. As has been shown, a long period must have 

 elapsed before this was the case; and if at the end of this 

 period, the humid climate of Quaternary times was giving 

 place to the later aridity, the lake would have no surplus 

 waters to discharge. Indeed, we know that many of the lakes 

 of this region never overflowed, even during the periods of 

 greatest humidity ; and with a large surface for evaporation 

 and comparatively small tributary drainage area, the lake in 

 question may never have had any surplus water to dispose of. 



The waters of Goose Lake do not appear ever to have 

 deposited tufa. The existing lake is very nearly fresh, con- 

 taining less than one thousandth of solids in solution, and is 

 ' inhabited by fish. Unfortunately there are no good exposures 

 in the bed of the ancient lake, and the character of its sedi- 

 ments is unknown. 



South of the region just described is a basin, drained by Pit 

 Biver, known as Warm Spring Valley. Although the district 

 has not been visited by the writer, yet from the topography it 

 seems safe to assume that this valley has also contained an 

 ancient lake which was drained by the cutting down of its out- 

 let. When the surface geology of this region shall be system- 

 atically studied, traces of many extinct lakes hitherto unnoticed 

 will no doubt be found. 



The next region to which these notes have reference is Sur- 

 prise Yalley, lying in the northeast corner of California. This 

 valley contained a Quaternary lake which never overflowed. 

 Its modern representatives are three shallow lakes occupying 

 the deepest portions of the basin, and known respectively as 



