Friday, July 17, 2009
Dynamics of the NW USA and Canada, from the Rockies to Vancouver Island
There has been a movement of the broken-off plate, now named Juan de Fuca plate- from a part of the Pacific plate- relatively eastward under the NA continent to create the Cascade Mountains (vulcanism), during the Tertiary. My interpretation of the breakaway is that the eastern edge of the Pacific plate began to be rotated by Coriolis forces, after moving into the continental shelf shallow water (thicker crust). Coriolis rotation becomes more noticeable, for the continents because the crust is thicker there than for the ocean basins. The likely interim event was a westward movement of the continent to encounter part of the Pacific plate, and to cause part of the plate to rotate along the N. California to Canadian border. The most northerly volcano exists almost at the international border (Cheam Peak), and the most southerly is Mt. Lassen at 40 degrees Latitude. Incidentally, this latitude is the approximate northern border of the Equatorial Bulge, EB, which is the latitude above which Coriolis forces have a lesser influence (because of the lack of the extra-thick Crustal bulge, going northerly).
Because of the exit of the Pacific plate from EB, several entities become more noticeable:
A. The minor plate- Juan de Fuca- moves independently of the northern movement of the Pacific Plate;
B. The tectonics of the region are not dominated by the larger Coriolis cells- such as B&R and CP, which are operating in the EB;
C. Vulcanism occurs at the edge of the boundary of the SdF-continental system, but not further north than the 50N Latitude (not counting Alaska, where the Pacific plate subduction still dominates). Yellowstone is related to the positioning of the rotating CP, where the greater Crustal thickness of the Rockies causes a faster Coriolis movement (similar to Jemez Mt. and Mammoth Lakes) and opening of the Crust to allow super volcanoes;
D. North of the Canadian border, the obvious curvature of the east and west coasts of USA ceases- indicating that Canada is mostly not involved in the rotation of the great Coriolis cell including the USA and part of Mexico; and,
E. The NW has many string lakes, oriented partly in N-S directions, but also in circular patterns in central and east Canada.
Cheam Peak, B.C. Canada, just north of US border.
Notice in the Google photo above, that the Coriolis rotation (as shown by circular or arcuate coastlines) is offset by other tectonics, starting at the Puget Sound area. Recall that the most northern Cascade volcano (Cheam Peak) is just north of the Canada border. The most southerly active Cascade volcano is Mt. Lassen, CA, at about the 40N Latitude. This allows the determination of the boundary of EB which is somewhat less than 50N Latitude. We will extrapolate the "expected" rotation path(should there have been no interference). This is shown below:
The larger "picture" shows that the glacier movement has obscured the Coriolis rotation in the east, while impingement of Terranes has offset the traces in the west. There is a major interaction of the two regions, inside and out of EB, at about the 50N Latitude. My intuition suggests that the north boundary of EB is playing a large part in the location of contrasting tectonic features.
An atttrmpt was made to find the larger coriolis cell dominating the whole MT-W. Canada region. Part of this feature is seen in the above photo, but the analysis has been distorted by the slide of ice during the Pleistocene- obscuring the earlier traces on the Google map. The lakes formed by the glaciers remain, but the surface rock and soil has been rearranged- masking the vital fractures and rearranging the river paterns (due to young streams being dominated by glacial flow). We will attack the string lake orientatin first, since these can be sorted from the obvious arcuate waterways- which are related to Coriolis Forces. A string lake will be defined as one with little curvature, or one that has random variations of its trace on the Google map.
Notice in the photo above, that there are two patterns: roughly N-S and NNE-SSW. The N-S trend (Seattle lakes) seems to be related to the subduction of the crust producing the Cascade N-S array of volcanoes (Tertiary, younger than Laramide). The other trend is definitely not oriented parallel to the Rocky (Laramide, or Mesozoic) Mountains- consequently being younger in age of formation. Coriolis cells are operating NOW, and must be sorted out from the String lake patterns.
To sort this out, contrast the portait with that seen in Quebec (east Canada, within the Shield):
The tendency is for the few lakes found to orient either N-S or NNW-SSE (hinting a continental bifurcation).
Elimination of the westward movement. for viewing of the west without this complication, of the NA continent may be made by determining the track, via extrusives moving apparently eastward, which has occurred during theTertiary. This is shown below for the states of ID, MT, and WY:
The above portrait is difficult to analyze, so let's look at the larger picture of the movement of the large cell forming the Yellowstone anomaly- which is presented by the Snake R. plain and entities north of the CP-B&R couplet:
Notice that the Rocky Mountains have been shifted by the rotation of the extrusion zone about the Yellowstone feature. My previous analysis was that the higher protrusion of the Rockies creates a thicker crust which is rotated faster than the neighboring Crust- causing a fractured or weak zone, from which magma can more easily move vertically. This allows larger super volcanoes, proportional to the protuding mass. Consequently we find other super volcanoes in similar circumstances: Jemez near the Rocky Mt. on the SE corner of CP, and Mammoth extrusion off the edge of the Sierras on the SW corner of the CP-B&R couplet.
The complexity of the NW is shown in the following Google photo:
My interpretation of the island surrounding the Hot Spring north of Tofino, Vancouver, B.C. shows that the region is breaking up, displacing the Coriolis cell adjoining the spring (see concave-westward RED arc). This arc becomes a concave eastward arc to the north (see lines in blue, along waterways). It appears that a portion of the island is displaced to the west at the junction of the colors.
An expanded view of the Tofino town and Flores Island is shown, undoctored, so that you see the location, for your future visitation (it is rigorous to climb into this spring-bath, and a boat ride is necessary from Tofino- which is reachable by auto)
Other anomalies investigated, for geologists inquiring about features on which they were interested, include a separate island off the mainland of B.C.- that of Jervis Inlet to Powell River mouth. The Google photo below shows an analsis of a double (almost) cell, which is evidentally breaking off from the mainland, under the impetus of the contrast of the continental movement to the
SW (by GPS) conflicting with the northward movement of the Pacific plate (subducting under Alaska).
Below is a photo of Cape Mendocino, which is an impportant feature for understanding the subduction and subsequent rotation of the minor SdF plate under the NW USA. Notice Sugarloaf Island, which is a "haystack" located just offshore of the Cape.
Below is a photo of the Mendocino, CA location- showing the area of my next investigation (I will visit it this August). This is an important area for clues for the transition of Coriolis rotation to shear, going westward under the Pacific Basin.
Part of the interesting features near Mendocino is the Fern Canyon State Park, near the mouth of the Klamath River. The river is part of a Coriolis cell, evidently sinking- causing CW rotation. We will check this along the K. River, to see whether slickensides have fornmed on the canyon walls.
Below the photo is rotated at right angles to show more of the canyon area. Notice that there is a partial cell, which seems to be dragged CCW (I'll check this in the field, since this is my greatest source of error- finding drag and rotation direction.
If my analysis is correct, there is counter-rotation upon crossing the Klamath River (so that there is no shear and subseqaunt metamorphism or heat produced- since the cells rotate as gears with no interference).
Crater Lake, OR and the Rogue-Umpqua River complex
Below is shown a portion of the Rogue River, OR, where the water flows underground for a few hundred meters- through lava tubes and fractures. This part of the river path is interpreted by me as being a place where the rotation of a Coriolis cell can be seen on the ground (since the river which would normally obscure the path now flows underground). Hence, if there is any circular fracture or lateral fault incurred by the shearing of the cell, it would show up as a trace above the path of the river.
Closeup photos show part of the basalt flow, which covers subsurface flow of the Rogue. The river can be seen entering and exiting an opening in the basalt, ustream and downstream. This is a significant river flow, which is in an arcuate path along the regional river valley.
Altjhough the river is explained locally as flowing through lava tubes, it can be seen to exit through enlarged fractures also. I interpret this whole sequence as follows:
1. Extrusives cover normally compacting deposits;
2. The vulcanism cools after the eruption;
3. The cooling (or heating) causes rotation of the ground surface, as the mass changes volume;
4. The volume change is accompanied by rightward movement of the Coriolis cell- creating lateral faulting along the path;
5. The regional drainage finds the fracture-faulting and creates a river valley;
6. Although most of the lava tubes orient perpendicularly to the regional fractures, some of them orient along the path of the fractures; and,
7. The Rogue River re-oriants along the circular path of the still-moving rotation.
TO BE CONTINUED: