192 NT GEOLOGY. 
this respect resembles the ordinary rushes.and flags of the New England States. It is like our 
large bulrushes in its form, but grows to an enormous size, attaining a height of from 8 to 15 
feet, and sometimes a diameter of three-quarters of an inch. This plant occupies the ground to 
the exclusion of other forms of vegetation; there are no shrubs or trees to overshadow it, and it 
constitutes a remarkable feature of the vegetable physiognomy of California. 
The rivers tributary to the lakes enter by numerous mouths ; they, in fact, form broad deltas, 
that are covered with vegetation. The character of the vegetation along the Four Creeks has 
been described ; it extends along the whole course of the stream and its sloughs, but it is prob- 
able that the trees which grow in such thick groves near the mountains become less numerous, 
and finally disappear in the lower and more marshy portions of the course of the river. 
The supply of water to these lakes must be very great; King's River and Posuncula River are 
large streams, and do not become exhausted in the dryest seasons. During the early part of the 
summer, or when the snows in the Sierra Nevada commence to melt rapidly, they convey 
enormous quantities of water, and the level of the lakes is raised. This constant variation in 
the quantity of water carried to the lakes, and the changes from the wet to the dry season, have 
the effect to keep the level of the water continually changing. This is one of the great pecu- 
liarities of the lakes, and the shallowness of their beds, and the low, shelving form of their 
shores, causes an unusual addition of water to become immediately evident by the wide-spread 
submergence of the surrounding country. 
These inundations are most extensive in the rainy season. Plains that have been scorched 
and cracked by the long drought of summer are overflowed, and the sun-baked soil absorbs 
enormous quantities of water. The lakes become greatly increased in length and breadth, and 
cover portions of the plains that, a short time before, had all the characteristics of a desert. At 
these periods of high water, the lakes sometimes communicate with the San Joaquin River by a 
slough or channel at the northern extremity of the Tulare Lake. This slough is like a canal, 
and is very deep near the San Joaquin, but eight or ten miles from this river it divides up into 
numerous channels, which become intricate and ramified as they enter the lake. It is said that 
when the level of the river is greatly raised by freshets it overflows its banks, and the water 
passes to the lakes by this slough. At seasons of low water, all communication between the 
river and lake is prevented by a bar at the mouth of the slough. In the dry season this slough 
may be crossed without finding water; and it has been customary to drive cattle across near the 
end of the lake. 
When we were encamped at Fort Miller, (July, 1853,) a party of rangers, who had killed the 
notorious bandit, Joaquin, arrived, and had been obliged to swim the slough, and one of the 
prisoners was drowned. 
We know but little of the country west of the Tulare Lake, between it and the mountains, OF 
of the plains lying between this lake and the smaller lakes at the south. At the time I crossed 
over to the western portion of the valley, no water was found until I came within a few miles of 
one of the outlying ridges of the western range. Here progress was stopped by a narrow sheet 
of water, or a marsh, in which the water was warm, muddy, and. slightly saline. It was 
extremely offensive to the taste, and the shores were soft and miry, and no vegetation, other than 
a few dried weeds, could be found. No current could be detected in this pool, but it is probable 
that it is a portion of the slough which connects the lakes together. unde 
Thick masses of saline incrustations were found about the shores, at the roots of tufts of dried 
“ bunch-grass," where evaporation had been most persistent and rapid. This incrustation 1$ 
