ground looked
like an asphalt pavement, half overgrown with marsh-loving weeds,
whose roots feed in the sloppy water which overlies the pitch. But,
as yet, there was no sign of the lake. The incline, though gentle,
shuts off the view of what is beyond. This last lip of the lake has
surely overflowed, and is overflowing still, though very slowly.
Its furrows all curve downward; and it is, in fact, as one of our
party said, 'a black glacier.' The pitch, expanding under the
burning sun of day, must needs expand most towards the line of least
resistance, that is, downhill; and when it contracts again under the
coolness of night, it contracts, surely from the same cause, more
downhill than it does uphill; and so each particle never returns to
the spot whence it started, but rather drags the particles above it
downward toward itself. At least, so it seemed to us. Thus may be
explained the common mistake which is noticed by Messrs. Wall and
Sawkins {148b} in their admirable description of the lake.

'All previous descriptions refer the bituminous matter scattered
over the La Brea district, and especially that between the village
and the lake, to streams which have issued at some former epoch from
the lake, and extended into the sea. This supposition is totally
incorrect, as solidification would have probably ensued before it
had proceeded one-tenth of the distance; and such of the asphalt as
has undoubtedly escaped from the lake has not advanced more than a
few yards, and always presents the curved surfaces already
described, and never appears as an extended sheet.'

Agreeing with this statement as a whole, I nevertheless cannot but
think it probable that a great deal of the asphalt, whether it be in
large masses or in scattered veins, may be moving very slowly
downhill, from the lake to the sea, by the process of expansion by
day, and contraction by night; and may be likened to a caterpillar,
or rather caterpillars innumerable, progressing by expanding and
contracting their rings, having strength enough to crawl downhill,
but not strength enough to back uphill again.

At last we surmounted the last rise, and before us lay the famous
lake--not at the bottom of a depression, as we expected, but at the
top of a rise, whence the ground slopes away from it on two sides,
and rises from it very slightly on the two others. The black pool
glared and glittered in the sun. A group of island