(all
rights to this material retained by author)
A
Review of the Historic Oil Wells
of the
Little Spokane River Valley
&
Regions
Around
(part
five)
by
Wally
Lee Parker
… a
sea of molten rock ...
Over
an eleven million year period — ending just six million years ago — an
estimated forty-one thousand cubic miles of basalt flooded up from beneath the
earth’s crust and then out and over sixty-three thousand square miles of what
would eventually become the states of Washington, Oregon, and Idaho. If collected into a single mass, this molten basalt
would form a sphere just under forty-three miles in diameter. If that sphere were allowed to empty out
across the surface of Eastern Washington — meaning just that portion of the
state to the east of the crest of the Cascade Mountains — it would cover the
land just a hair’s breadth more than a mile deep in basaltic rock. Poured out in hundreds and hundreds of
separate molten extrusions, this incomprehensible deluge of lava has managed to
obscure vast stretches of the older lands beneath a sizable portion of the
three above noted states — much to the benefit of early 20th century
oil speculators.
But
in all of this space, there is nothing rising significantly above the surface
resembling a traditional volcano.
One
of the more insightful early scientific observations of the Pacific Northwest’s
various outpours of molten rock occurred in 1879. Scottish geologist Archibald Geikie
(1835-1924) of the British Geological Survey had been invited by his North
American scientific colleagues to tour the far western United States. Writing in an engagingly non-technical style,
Sir Geikie penned an article about this expedition which appeared in the
October, 1881, issue of the British periodical Macmillan’s Magazine under the title “The Geysirs of Yellowstone.”
 |
| Sir Archibald Geikie (1835-1924) |
Sir
Geikie, with an unnamed travelling companion, rode the then ten year old
transcontinental railroad from the eastern seaboard to Ogden, Utah, and from
there traveled north by narrow-gage rail, stagecoach, and carriage to Fort
Ellis near Bozeman, Montana. At Fort
Ellis Geikie presented a letter of introduction provided by “authorities at Washington” (probably
agents of the United States Geological Survey), and “arranged to travel
through the Yellowstone Park, as it is termed, and through the Mountains
encircling the head-waters of the Snake River.” In his story, Sir Geikie explained that Yellowstone
Park was “that region of geysirs, mud
volcanoes, hot springs and sinter-beds, which the United States Congress, with
wise forethought, has set apart from settlement and reserved for the
instruction of the people.”
The
military provided Sir Geikie and his companion with horses, mules, a guide, and
a mule handler. The four men packed
through Yellowstone — visiting the geysers (or “geysirs,” as it was then spelled) — and then west over the “great divide” and down to a stream
called “Henry’s Fork, one of the feeders
of the Snake River.” Following this
steam through miles of forest, they eventually found themselves “picking” their “way across a dreary plain of sage brush on the edge of the great
basalt flood of Idaho.”
Sir
Geikie’s “great basalt flood of Idaho,”
at least the part he visited, isn’t part of the Columbia flood basalts. Geikie’s flood basalt is actually part of
the outpouring from Idaho’s much later great rift valley — though that was
likely not evident to the geologists of the time.
Near
the conclusion of his story, Sir Geikie wrote, “The last section of our ride (his time in Idaho) proved to be in a geological sense one of
the most interesting parts of the whole journey. We found that the older trachytic lavas of
the hills had been deeply trenched by lateral valleys, and that all these
valleys had a floor of the black basalt that had been poured out as the last of
the molten materials from the now extinct volcanoes. There were no visible cones or vents from
which these floods of basalt could have proceeded. We rode for hours by the margin of a vast
plain of basalt stretching southward and westward as far as the eye could
reach. It seemed as if the plain had
been once a great lake or sea of molten rock which surged along the base of the
hills, entering every valley, and leaving there a solid floor of bare black
stone. We camped on this basalt plain
near some springs of clear cold water which rise close to its edge. Wandering over the bare hummocks of rock, on
many of which not a vestige of vegetation had yet taken root, I realized with
vividness the truth of an assertion made first by Richthofen (most likely
referring to Ferdinand van Richthofen, German geologist, 1833-1905), but very generally neglected by
geologists, that our modern volcanoes, such as Vesuvius or Etna, present us
with by no means the grandest type of volcanic action, but rather belong to a
time of failing activity. There have
been periods of tremendous volcanic energy, when, instead of escaping from a
local vent, like a Vesuvian cone, the lava has found its way to the surface by
innumerable fissures opened for it in the solid crust of the globe over
thousands of square miles.”
Although
Geikie was walking on relatively recent flows — most likely millions of years
younger than the last of the Columbia basalts — the eruptive mechanisms that
eventually filled the eastern reach of southern Idaho’s Snake River Plain often
mirror — though not exclusively — those of the Columbia flows. In that regard Geikie’s statement “Bare hummocks of rock, on many of which not
a vestige of vegetation had yet taken root” could very well describe the
floor of the Little Spokane River Valley in those years after the great
basaltic tides of Columbia lavas had flooded in from the south, but before the
subsequent millions of years of erosion, sedimentation, and glacial disruption
had turned the valley’s floor fertile once again.
In
1892 Professor Edward Hull (1829-1917) of the Royal College of Science, Dublin,
in his book Volcanos: Past and Present,
wrote of the actual Columbia flows, “The
absence, or rarity, of volcanic craters … in the neighborhood of these great
sheets has led American geologist to the conclusion that the lavas were in many
cases extruded from fissures in the earth’s crust rather than from ordinary
craters.”
As
for the American viewpoint, in 1897 geologist Israel Cook Russell (1852-1906)
penned a dramatic description of the Columbia basalt floods for the abstract
of his U. S. Geological Survey paper,
Principle Features of the Geology of South Eastern Washington.
“The Columbia lava flowed about the bases of
the mountains of Eastern Washington and the adjacent portion of Idaho in a
series of inundations which covered the low country to the south. The level basaltic plateau meets the
mountains … in much the same manner that the sea forms a rugged and deeply
indented coast. The lava entered the
valleys and gave them level floors of basalt; the deeply sculptured ridges
between the valleys were transformed into capes and headlands; outstanding
mountain peaks became islands in the sea of molten rock.”
Evidence
of this basalt infilling can be found both on the surface and below the surface
of the Little Spokane River Valley, where at least several of these massive
floods poured north over the present day site of Spokane to form molten lakes
between the low, rounded mountains rising east, west and north of the
valley. Remnants of these floods suggest
the last invading flow reached more than a hundred feet above the present day
level of the little town of Clayton.
Israel
Russell also stated, “The great fissure
eruptions which supplied the Columbia lava, as the basalt is termed, occurred
in the Miocene,” — suggesting that the geologic community had early on
assumed as solved both the manner of upwelling and general age of these ancient
flows. And the United States Geological
Survey concurs that the Columbia Plateau basalts were formed by over three
hundred separate outpours occurring periodically between seventeen and six
million years ago — within what geologist recognize as the Miocene epoch.
Using
laboratory and computer modeling, as well as extensive field studies,
geologists have been able to visualize just how magnificent and terrifying one
of these molten floods would have been.
Accompanied by ongoing tremors as the older lands around these monstrous
clusters of fissures settled downward to replace the extruding magma, these
floods of highly viscous lava are calculated to have poured across the surface
at an average speed of perhaps five miles an hour. Although that doesn’t sound impressive, if
the pace was steady the flood’s front could travel 120 miles every 24
hours. Even the fastest earthbound
animals, all made of fatigable flesh, couldn’t escape that — as the hollow casts
of various Miocene era creatures entombed by the lava clearly shows.
But
how could lava have continued to flow hundreds of miles from the point it
squeezed out of the earth’s surface?
Evidence suggests that the leading edge of the flood could easily have
been a hundred feet high. The relatively
cold crust forming above the flow would have acted as insulation, keeping the
lava flowing underneath super-hot (as can be observed today with much smaller
lava flows). Just like the flow’s upper
surface, the leading edge would have continually tried to form a solid skin as
it — being exposed to the air — cooled.
And the blistering lava behind the blackening leading edge would have
continually broken through the crust, billowing forward in luminous tongues, stuttering
in the direction of least resistance.
Finding
obstructions such as highlands, mountain peaks, or canyon walls, the flow’s
forward momentum would still into lakes of lava. From there it would gather higher and higher,
until it overflowed the obstacle, found a way around, or began flowing in a new
direction. When the outpour finally
stopped, it might take several years for the congealed flood to fully cool.
The
new surface left behind would not be smooth. Though relatively level, this ragged plane of
cooling basalt would prove a vast field of lifeless stone, broken into jagged
razors of rubble. It would be strewn
with cracks, pits, and mounds, making movement across these newly formed beds
difficult in the extreme. And then,
through passing ages of cycling sun and snow, rain and wind, physical and
chemical erosion would tear the rocks apart, crumbling the surface into soil. Streams and rivers would cut canyons. Ponds and lakes would form. A few thousand years, or even hundreds of
thousands of years would pass between eruptions. If the quiet was long enough, the jagged
terrain might even erode into gently rolling grassland. But eventually the floods of blistering rock
would return, covering everything, and the process would begin again.
As
for the forces driving the uplifts that cracked the earth’s surface into swarms
of volcanic vents —into swarms of crustal rips that slowly moved north along
the Oregon/Idaho border and into the southeastern tip of Washington State — the
root of that story begins approximately 750 million years ago in the interior
of the supercontinent of Rodinia.
Current
tectonic theory suggests that the earth’s continental plates — massive,
eggshell like fragments of solidified crust — are in constant motion, colliding
and ripping apart as they slide over the viscous magma of the planet’s molten
mantel. Geologic hypothesis speculates
that the process of supercontinent formation of which Rodinia is a part began
about 3½ billion years ago — not long (geologically speaking) after the earth’s
condensation from the solar system’s primordial cloud — and that four or five
previous supercontinents had existed and broken up in turn before the Rodinia
supercontinent came together. In general,
as these supercontinents break apart, the fractures first become visible as
rift valleys. These spreading valleys
eventually become inland seas, and then — as these fractured lands drift apart
(or more apply are pushed apart by upwelling currents of superhot magma rising
out of the earth’s deep interior) — the seas between become oceans.
750
million years ago the Pacific Northwest segment of what would eventually become
the North American continent was wedged within the interior of the above noted
supercontinent of Rodinia. For some time
the part of the supercontinent that would eventually support the towns of
Spokane, Deer Park, and Clayton was likely an inland flood plain, sequentially
covered by in-washes of muddy sediments.
The evidence for this is found at an outcropping of some of the oldest
rock so far discovered in the State of Washington — an ancient deposit on
Prosser Hill just southeast of the small town of Four Lakes in western Spokane
County. Described as a meta-sedimentary
stone showing mud cracks and ripple marks consistent with deposits forming in
shallow lakes or along slow moving riverbeds — both subject to periodic drying —
this road cut exposure of crumbling slate-like rock is located at —
approximately — the 2,500 foot level on the northeastern slope of the
hill. Geologists have dated this
mudstone to the middle Proterozoic — 1 billion, 200 million years ago.
 |
| Prosser Hill Mud Stone (photo by author) |
According
to current thinking — and in relation to the present day Pacific Northwest —
the rift fracturing the crustal plate of Rodinia in the late Proterozoic Eon
would have trended in a north/south direction several dozen miles west of the
towns of Spokane, Deer Park, and Clayton.
This would have left the future site of these towns teetering on the
very edge of the new North American continental plate. Forming part of the continental shelf, it’s
probable that this area would have subsided below the newly forming Pacific
Ocean as the opposite side of the rift was pushed away, and ongoing volcanic
extrusions formed a new ocean bottom in its place. The actual beaches of North America’s new
coast would have likely surfaced out of the primal ocean some distance to the
east of this opening rift — suggesting that the town of Deer Park would have
never been prime ocean front property.
As
the Pacific Northwest’s former self slowly drifted away to drop over the
earth’s curvature — drifted away to eventually becoming part of present day
China — the leading edge of the new North American plate entered a long period
of geologic quiescence. Geologically
speaking, the Pacific Northwest became a coastal backwater.
By 300 million years ago
the other side (currently the eastern side) of the North American plate had
welded itself into Pangaea, the next supercontinent to form. Pangaea held together for another 100 million
years. Then, as a massive complex of
rifts began separating the North and South American continental plates from
Asia, Europe, and Africa some 200 million years ago, Pangaea in turn began to
rip apart — the complex of dividing cracks eventually becoming the Atlantic
Ocean.
Even
today the Atlantic Ocean continues to expand, and new crustal materials are
volcanically extruded along what is now called the mid-Atlantic ridge. Current hypothesis suggests that it’s a set
of massive thermal currents rising from deep in the earth that are pushing the
North American plate in a westward trending direction — essentially pushing the
North American plate across the Pacific in pursuit of its former self. Due to this “new” planetary paradigm of some
200 million years ago — as the North American tectonic plate began to move,
began to drift over the earth’s surface — the Pacific Northwest’s period of
geologic quiescence ended.
In
the wake of the Pacific Northwest’s long separated “Chinese” part, the forces
of plate tectonics (continental drift) left a litter of newly formed plates on
the ocean’s floor and towering volcanic islands resting on those plates. As the American continent began scooting
westward across the Pacific at an average of two inches a year, it began
colliding with this newly extruded material.
In general the floor of the Pacific basin is being pushed down and under
the overriding mass of the North American plate — though at times portions of
the plates being overridden and the volcanic islands riding on top of those
plates have been scrapped off the down and under moving plates. These scraped lands then collide and weld
into the oncoming mass of the North American continent. As a result, the coastline of the Pacific
Northwest continues to expand to the west as new lands are melded onto the
coast. In the last 200 million years this
process has added over 300 miles of new continental land to what was once the
leading edge of the Rodinia rift.
One
of the side effects of pieces of the former Pacific Basin plunging beneath the
overriding North American plate is the generation of tremendous amounts of
frictional heat. This massive heat melts
the subducting rock — the down-diving rock — leaving vast pools of magma
relatively close to the earth’s surface.
All the while the North American plate continues its slow westward
migration over the top of these newly formed hotspots. It’s believed these subduction induced
hotspots melting their way upward through the earth’s crust are the primary
cause of volcanism throughout the Pacific Northwest — including the volcanism
that forced the molten Columbia basalts through cracks in the earth’s
surface. It’s also believed that these
subduction induced hotspots are the reason for the cracks.
When
thinking of rock as a fluid, the same general principles apply as to any other
fluid. Heat stored within a fluid tends
to migrate into the walls of the containing vessel. If that containing vessel is rock, the
containing rock will warm. If the fluid
being contained is hot enough, the amount of heat moving into the containing
rock will melt it — turning it into molten magma as well. Since warmer fluid rises and colder fluid
sinks, the newly melted and generally cooler lava at the top of the containment
vessel will tend to sink and be replaced by hotter lava from beneath. Due to the natural bias of heated materials
to rise, this hotter lava will continue melting its way upward through the once
solid rock.
This simple principle of
heat migration outlines how vast pools of magma can rise to the surface through
an overburden of solid crust. As the
pools approach the thinning surface they often bulge the still solid crust
upward. Stress cracks — rips — tend to
form as a result of the increasing surface area of these stressed, dome-like
bulges. And these surface rips are the
areas of weakness through which the upward-pressing molten rock can find a
pathway to the surface.
This is believed to be the
basic geologic mechanics that allowed the Columbia basalts to repeatedly flood
across the states of Oregon, Washington, and Idaho.
Evidence
of Israel Russell’s “great fissure
eruptions” is found in the form of what geologist call dikes. A dike is the infilling within a cleft opened
within pre-existing rock. When crustal
fissures ripped through the existing rock surface and the lava being pushed up
and out of these fissures eventually stopped, what remained within the fissure
would cool and solidify. Chemical,
magnetic, and visual differences between the original surface rock and the
infilling rock of the dike can reveal the fissure and therefore the site of
eruption. In some instances the
melt-edges of the original rock through which these lavas have pushed prove
more resistant to erosion than the outpoured lava, allowing the vent dikes to
stand out in relief as the lavas around them erode away. These dikes are usually no more than a dozen
feet wide, though miles in length. And
the fissures tend to cluster in swarms — the swarms covering areas a mile or
two wide and 30 to 120 miles long. With
some variation, these vents tend to align themselves in a roughly north/south
direction — suggesting they are following the primordial subduction fault lines
originally traced along North America’s archaic coast.
As
far as chemical traces and exact percentages of mineral ratios are concerned,
volcanic materials erupted from different sites are never exactly alike. These minute differences can act as fingerprints
— allowing specific lavas to be grouped together as to source. When visible, source dykes can be identify by
analyzing — by fingerprinting — the materials frozen in their throats. A large number of the Columbia basalts have
been mapped by tracing these unique chemical signatures across hundreds of miles
of flows. Though much work is yet to be
done, each year the picture becomes a little clearer. But through it all, the discoveries made
since Archibald Geikie, Professor Hull, and Israel Russell’s day have done little
to alter these men’s original descriptions of the Pacific Northwest flood
basalts. Once these outpours truly were
a sea of molten rock.
Geologists
have also determined that the Selkirk Mountain Range once continued hundreds of
miles to the south of present day Mount Spokane. Other than a few isolated peaks, most of
these mountains have disappeared — have sunk as the vast pools of lava beneath
emptied out onto the surface and the original surface sank, taking the
mountains with them. Steptoe Butte,
approximately 40 miles south of Spokane, is the top of one such sunken mountain.
As
for what the original land was like — the lands now buried with the southern
reach of the Selkirk Mountains — some clues can be gained from looking to the
land both north and south of the Columbia Plateau. Otherwise — and especially in the early 20th
century — most anything could be imagined beneath this basaltic overburden. And the Inland Empire’s early oil prospectors
seemed to imagine whatever might prove most profitable.
… to be continued …
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