32 GEOLOGY OF SW. IDAHO AND SE. OREGON. [bfll.217; 
The inner slopes of the valley in which Malheur and Harney lakes 
are situated are not scored with old beach lines or terraces, as is the 
case in so many of the similar valleys of the Great Basin. This is 
consistent with the low elevation of the old river channel leading- 
eastward from the valley to the headwaters of Malheur River. As 
already stated, the present hydrographic basin of Malheur and Har- 
ney lakes was formerly a part of the Malheur River drainage system, 
and was cut off by a lava flow which entered the channel of the former 
and greater Malheur River. On account of the small precipitation 
and active evaporation in the region above the broad lava dam, the 
water in the basin thus cut off has never been able to rise sufficiently 
to cross the obstruction which retains it. The evidence thus f urnished, 
tending to show that Malheur and Harney lakes are not remnants of 
a former large water body, is also in harmony with their chemical 
composition. Their present degree of salinity indicates but a com- 
paratively short period of time since the dam which retains them was 
formed. The lava sheet referred to is, however, covered with a thin 
soil, and supports a rank growth of sagebrush, indicating that it is 
much older than the ver} 7 recent lava flows about the Diamond, Bow- 
den, and Jordan craters, to be described later. 
SILVER LAKE. 
In the valley of Silver Creek, about 11 miles northwest of Harney 
Lake, there is a small, shallow water body, termed Silver Lake, and 
sometimes referred to as Little Silver Lake to dist'nguish it from 
another and larger water body of the same name situated in Lake 
County, Oreg. The basin in which Silver Lake is situated is broad 
and flat, with indefinite boundaries, and during high-water stages 
becomes a wide expansion of the creek which flows through it. In 
summer the creek ceases to flow, and the lake is kept from evaporat- 
ing to dryness by the contribution received from a hot spring on its 
southern border. 
Several basins along the somewhat indefinite course of Silver Creek 
between Silver and Harney lakes become flooded in winter and com- 
pletely desiccated in summer. When dry the floors of these shallow 
basins become absolutely'barren mud plains or playas, some of which 
are 3 or more miles across. These yellowish floors of dried mud are 
sufficiently hard in summer to be crossed with a loaded wagon with- 
a bay, about 100 miles in diameter, known as the Karaboghaz, or "bitter lake," which is. con- 
nected with it by a strait -150 yards wide and 5 feet deep. The Karaboghaz has no inflowing 
streams and no outlet. The climate is arid, and on account of the loss from its surface by evap- 
oration a current sets into it from the Caspian at a rate of from If to 3 miles per hour. As com- 
puted by Van Baer, the amount of saline matter carried by this current is 350,000 tons per day. 
The Caspian is thus losing saline matter probably at a greater rate than it is being supplied, and 
the water of the Karaboghaz has been concentrated to such an extent that it is a saturated 
solution, and contains something like 24 per cent of saline matter, and from it common salfy is 
being deposited. An instructive example is thus furnished of one method by which a saline 
lake may be relieved of its salts, and of one method also by which saline matter is concentrated 
and deposited in a solid form. 
