ing between
precipitous, although not very lofty, ranges; the western half is
magnificently timbered, and toward the coast excessively wet. Between 35
deg. and 36 deg. N. lat. the Sierra at its southern end turns westward
toward the coast as the Tehachapi Range. The valley is thus closed to
the north and south, and is surrounded by a mountain wall, which is
broken down in but a single place, the gap behind the Golden Gate at San
Francisco. Through this passes the entire drainage of the interior. The
length of the valley is about 450 m., its breadth averages about 40 m.
if the lower foothills be included, so that the entire area is about
18,000 sq. m. The drainage basin measured from the water-partings of the
enclosing mountains is some three times as great. From the mouth of the
Sacramento to Redding, at the northern head of the valley, the rise is
552 ft. in 192 m., and from the mouth of the San Joaquin southward to
Kern lake it is 282 ft. in 260 m.

Two great rivers drain this central basin,--the San Joaquin, whose
valley comprises more than three-fifths of the entire basin, and the
Sacramento, whose valley comprises the remainder. The San Joaquin is a
very crooked stream flowing through a low mud-plain, with tule banks;
the Sacramento is much less meandering, and its immediate basin, which
is of sandy loam, is higher and more attractive than that of the San
Joaquin. The eastward flanks of the Coast Range are very scantily
forested, and they furnish not a single stream permanent enough to reach
either the Sacramento or San Joaquin throughout the dry season. On the
eastern side of both rivers are various important tributaries, fed by
the more abundant rains and melting snows of the western flank of the
Sierra; but these streams also shrink greatly in the dry season. The
Feather, emptying into the Sacramento river about 20 m. N. of the city
of Sacramento, is the most important tributary of the Sacramento river.
A striking feature of the Sacramento system is that for 200 m. north of
the Feather it does not receive a single tributary of any importance,
though walled in by high mountains. Another peculiar and very general
feature of the drainage system of the state is the presence of numerous
so-called river "sinks," where the waters disappear, either directly by
evaporation or (as in Death Valley) after flowing for a time beneath the
surface. These "sinks" are therefore not the true sinks of limestone
regions. The popular