30 BULLETIN 54, V. S. DEPARTMENT OF AGEICLTLTUEE. 



THE GOOSE LAKE BASIN. 



South of the Abert Basin, but without any certain structural relation thereto, is 

 another north-south trough in which lies Goose Lake, between the Warner ^Mountains 

 on the east and the IModoc lava plateau on the west. The southern portion of this 

 valley is occupied and drained by the Pitt River, the northern, or Goose Lake por- 

 tion, being separated therefrom only by an alluvial divide just south of the lake. 

 This di^'ide is apparently recent and is now only a few feet above the lake. It is 

 probable that the lake has frequently overflowed it, and indeed it is reported that this 

 has occasionally happened within the memory of present inhabitants. Undoubtedly 

 the freshness of Goose Lake is to be thus explained. 



THE MADELINE BASIN. 



On the lava plateau north of the Honey Lake Basin is the very similar basin of the 

 Madeline Plains. The structure of its Avails is very irregular and in many places the 

 divides are not exactly determinable. A number of low passes lead both to the Pitt 

 River drainage and to the Honey Lake Basin, and some one of these. may formerly 

 have served as a channel of overflow. However, old strand lines are visible at several 

 points about the basin and serve to indicate the existence and fluctuations of an 

 inclosed lake. Lentil passes and strands have been studied more exactly and compared 

 •with each other it is impossible to read with any assurance the history of this ancient 

 lake or to determine whether it overflowed or how long the overflow continued. 

 Still less is it possible to decide whether the overflow, if any, was into the Pitt River 

 or into Honey Lake. 



The present floor of the valley is flatand featureless, except for occasional dune 

 areas. There are many small local playas, but no area of general concentration is 

 noted on the available maps or was observed by the writer. The plain is nowhere 

 saline. At its southwestern corner an outlying tongue of the plain has been cut off 

 by a low alluvial divide and forms the Grasshopper Valley. This valley was evidently 

 once a part of the Madeline water body, but its subsequent relations thereto are uncer- 

 tain. It now contains a small march. The total area of the Madeline Basin, including 

 Grasshopper Valley, is about 900 square miles. 



THE MODOC LAVA BEDS. 



West and northwest of the Goose Lake Valley a series of great basalt flows stretches 

 westward to the volcanic uplift which culminates in Mount Shasta. Diversified only 

 by minor faults and folds and by a few deep and narrow canyons of erosion, the region 

 has not developed any extensive drainage system and advancing desiccation has 

 destroyed what little drainage there once was. The streams are dry and the occa- 

 sional shallow depressions are areas of inclosed drainage floored by local playas. The 

 region is not unlike that surrounding the Cliristmas Lake Valley as described on page 

 23, and, like it, has no importance to this inquiry. The small basins of the lava beds 

 are so tiny and their inclosed condition is so recent that salt accumulation in them is 

 practically out of the question. This applies also to the basin of Medicine Lake on the 

 western edge of the area near Mount Hoffman, though it is not so fully desiccated as 

 its analogues to the east. 



THE KLAMATH LAKES. 



On the northeastern border of the lava bed region are a series of shallow basins 

 holding the Klamath Lakes. The geologic history of this region has not been studied 

 in detail, but a brief examination of the major features has suggested to the writer 

 that the present lakes probably occupy local depressions in the bed of a much larger 

 lake, perhaps of late Tertiary age, which lake has been drained by the cutting of the 

 gorge of the Klamath River. A similar history, on a smaller scale, is to be ascribed 



