30 GEOLOGY OF SW. IDAHO AND SE. OREGON. [bull. 217. 
None of the springs rising in the neighborhood of Malheur and 
Harney lakes, it may be noted, are highly charged with mineral mat- 
ter in solution, and all their tributary streams are of clear, sweet 
water, unless it is in late summer, when they are greatly reduced in 
volume by evaporation. 
Malheur and Harney lakes are without outlet, except that during 
high-water stages the former sometimes overflows into the latter 
through a recently formed channel. The two lakes during their winter 
stages are separated by a narrow irregular ridge of sand dunes, which 
extends westward and borders Harney Lake for several miles. These 
dunes are composed of quartz sand, blown up from the shore of the 
lake during low-water stages by the prevailing westerly winds, and 
make a conspicuous range of hills in general about 100 feet high, 
in part grass covered, with steep-sided basins among them. Previous 
to the formation of these hills of wind-drifted sand the basins of Mal- 
heur and Harney lakes were not separated one from the other, at least 
during high-water stages, and but one lake existed. The water in this 
lake at the locality where the basin is now divided was shallow and 
during summer seasons, or at intervals of unusual desiccation, the bot- 
tom was exposed. During such a low- water stage, as seems evident, 
the winds drifted the exposed sands and formed a ridge which divided 
the preceding water body into two lakes. This was before white men 
visited the region. It is reported that during an unusually high- water 
stage in 1877, and aided, as I have been informed, by a furrow plowed 
for the purpose, the water of Malheur Lake broke across the ridge of 
sand referred to above and rapidly scoured out a channel leading to 
Harney Lake. This channel is now about a quarter of a mile long, 
30 to 40 yards wide, and from 6 to 10 feet deep. At the time of my 
visit, August 6, 1901, the channel was dry and the water of Malheur 
Lake had shrunk until only a few hundred acres to the south of The 
Narrows (a constriction in the lake near its southern end, now crossed 
by a bridge) were flooded; the Avater of Harney Lake had also been 
diminished by evaporation so that the lake's surface was from 8 to 10 
feet below the ridge of sand and gravel marking its preceding winter 
stage. The gravel ridge or beach line referred to was about on a level 
with the highest point in the newly formed channel, but the ridge, it 
will be understood, marks the upper limit of the waves generated dur- 
ing storms and not the usual level of the lake. In summer, when Mal- 
heur Lake is low, nearly the whole of the portion of its basin south of 
The Narrows is dry and converted into a pi ay a over which broad areas 
are white with alkaline salts, or overgrown with the familiar plant of 
alkaline valleys known as Salicornia (PI. TI, A). Nearly every winter 
season, as I have been informed by persons living in the vicinity, 
Malheur Lake rises and overflows into Harney Lake. Each lake is 
alkaline, but, owing to the delicate adjustment described above, Har- 
ney Lake is more strongly charged with mineral matter in solution 
