Nevada County CA Archives History - Books .....Geological 1867
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Book Title: Bean’s History And Directory Of Nevada County, California

GEOLOGICAL.

  Nevada county is entirely mountainous, lying wholly on the western water-shed
of the Sierra Nevada, and extending almost from the Sacramento valley to the
summit. The average descent of the surface from the top of the mountain range to
the valley is about one hundred feet to the mile.

  The strata, which strike north and south, corresponding with the direction of
the range, are generally of granite alternating with slate. Of the latter there
seems to be three distinct ranges at least. Besides rock of the slate and
granite order, syenite, serpentine, trap, limestone, talc and quartz, occur
frequently, as an examination of the banks of the rivers that cut these rocks at
right angles, and the various mines that have been opened, will show. Gold is
found in a talcose slate in the extreme lower part of the county. In Grass
Valley it occurs in quartz, sandwiched in greenstone or trap generally. About
Nevada the cab or country rock is granitic, and in the upper quartz belt, in the
vicinity of Meadow Lake, it is syenite.

  Lying upon the primitive strata, and extending over a good share of the
central portion of the county, are immense gravel ranges, the beds of ancient
streams, the date of whose formation is referred to the pliocene age. Out of the
gravel of these old river beds, up to this time, a large share of the gold of
the county has been extracted. Immense basins still exist untouched for want of
adequate drainage, and long reaches of the ancient streams are supposed to be
yet unexplored.

  The big blue lead of Sierra county is known to cross the Middle Yuba, the
northern boundary of the county, at or about Snow Point. From there it is
thought by some to run southwardly, and to connect with the blue cement diggings
at Quaker and Hunt's hills. Others suppose the lead to follow down the ridge
between the South and Middle Yubas, and to show itself in the gravel ranges at
Humbug, North San Juan and on to French Corral, terminating finally in the very
rich deposits worked by Pierce & Co., at Smartsville, in Yuba county. It is more
probable, however, that the grand range of North San Juan is a continuation of
another river bed formerly coming down thorugh Sierra county, at Camptonville.
The gravel range above the town of Nevada, and hut a half mile distant, is
thought to have some connection with the San Juan range by way of Round Mountain
and Montezuma Hill; but it is not impossible that it may continue beneath the
ridge between the South Yuba and Deer Creek, as that ridge is demonstrated to
rest on a bed of gravel, overlaid on the surface with lava to the depth of from
eighty to one hundred feet. But it is not possible to reconstruct the ancient
map of the county with the data thus far obtained. Undoubtedly when the region
has been thoroughly examined by Professor Whitney and his corps, much light will
be thrown upon this interesting subject. It is understood that Nevada county
will be thoroughly explored the coming season by the Professor and his
scientific coadjutors.

  Unlike the counties of Amador, Calaveras and Tuolumne, farther south, whose
gravel ranges are ascribed to the same era, Nevada furnishes no fossil shells,
or any organic remains whatever. In the former counties have been discovered
bones of the mastodon, elephant, rhinoceros and horse, and the scientific world
has been startled with the report of the discovery of even the remains of a man
who is supposed to have walked the earth anterior to or coeval with the filling
of these ancient river beds. Not a bone of an animal has been so far found in
the gravel drifts of Nevada county of which any report has been made. Why not
here as well as in other parts of the State? The most ready answer would be, its
more northern latitude. But this is not satisfactory, when it is known that
teeth of the mastodon have been discovered in the auriferous gravel of Idaho,
hundreds of miles still farther north, and the deposits in which these remains
were found are supposed to date their origin in the same era as the gravel
ranges of California.

  It seems to me that more untenable positions have been taken by geologists
than that which would ascribe the gravel ranges of California to causes now in
force. Why may not the present rivers running down the western declivity of the
Sierra Nevada, before their present deep channels were formed, have coursed
along those old channels now filled up with, gravel? There are some reasons for
believing that no great climatic changes have occurred since these old deposits
were made. The existence of petrified wood undoubtedly of the coniferse family,
oak and manzanita, and of wood either lignite or in almost its natural state, in
these auriferous gravel drifts, would seem.to indicate that our mountains were,
at the time these ancient, river beds were filled, covered with pine and oak as
at the present day. And. if so, why were they not inhabited? Indeed, the
discovery of the fossil, remains of man further south, coupled with the fact
which seems to be well authenticated, of the washing out of a stone arrow-head,
sixty feet from the surface, and on the bed rock, in the claims of Major Lewis,
at Buckeye hill, near Sweetland, would seem to prove that a race inhabited our
mountains at a period before the present river chasms were channeled, and before
the last run of lava from the upper Sierra. And if the climate of this region
has undergone no radical change, why may not the existence of the mastodon
further south be attributed to local attractions, which did not and do not
present themselves in this county? The productions of the county at present are
not calculated to give sustenance to large numbers of such animals, and it may
be that their scarcity, from like causes, precludes the possibility of their
remains being found here, and in but limited quantities, in places most
congenial to their habits. But these are questions we leave for geologists.

  High up in the Sierra granite or syenite mountains rise to an altitude of a
little more than 8,000 feet above the sea level, leaving gorges between of
fearful depth, the walls of which are often of ragged and bare rock. Sometimes
the declivities of the mountains, and the valleys present extensive beds of
detritus that may have been deposited when the mighty glaciers of the Sierra
were melted—abundant evidence of glacial action being frequent at that altitude.
The detrital deposits are of sedimentary lava, pebbles and bowlders of the.
material of the primitive rocks, and sand. In some cases large beds of sand
appear, and sometimes deposits of angular gravel, which have the look of ancient
moraines.

  The geological character of Nevada county is yet to be studied by competent
men. The time will come when the ancient map of the county will be made for the
benefit of students, and fortified with such evidences of truth as to leave
little if any doubt of its correctness.


Additional Comments:
Extracted from:

Bean’s History and Directory of Nevada County, California

CONTAINING A COMPLETE HISTORY OF THE COUNTY, WITH
SKETCHES OF THE VARIOUS TOWNS AND MINING
CAMPS, THE NAMES AND OCCUPATION OF
RESIDENTS; ALSO, FULL STATISTICS
OF MINING AND ALL OTHER
INDUSTRIAL RESOURCES.

COMPILED BY EDWIN F. BEAN.

PRINTED AT THE DAILY GAZETTE BOOK AND JOB OFFICE,
1867.


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