Thrusting on Whidbey I. west beaches, cont'd

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E-W fractures indicate orthogonality with strong N-S stressing of mid-Whidbey Island

A Close-up of Thrusting on Whidbey Island

There are thrust planes found in the cliffs on the west side of W.I.; these are undeniable, as analyzed in previous reports in earlier submissions. However, whether they are predominantly the work of glaciers, to the exclusion of other tectonics, must be demonstrated.
The photos above show that there are a fair number of small thrusts near the Hancock Lake, which is within two kilometers of the well-documented Fort Casey-Ledgewood-Baby Island NW-SE still-active fault zone. Since these change their appearance with the annual slumping and retreat of the cliffs near Hancock Lake, this raises some doubt about their incipience and magnitude.
One large thrust plane has not ameliorated with the years (shown in photos), even though several other large sheets noticed nearby have disappeared. This is shown in the cliffs just south of Hancock, and I have explained the entire phenomenon as due to the significant scarp there. Driving on the hiway 525 roadway near Greenbank, one can see the scarp, as the automobile chugs down, climbing it going south. This scarp is on the narrowest part of the mid-island, springs occur there, and the thrust plane is on the immediate south side of this scarp in cliffs.
I have suggested that one of the glaciers pushing south, rammed against this scarp, forcing the top layers to slide to the south- giving the appearance of a thrust sheet. Since the thrust plane is almost horizontal, this conjecture still seems reasonable. The fact that some of the associated thrust planes have disappeared over the years introduces some doubt. This disappearance indicates that whatever occurred was not of large lateral extent (except for the one plane remaining).
One confusing occurrence is that of cross-bedding in dunal sands, which sometimes appears in cliffs near by. Inter-dunal zones, which may occur above and preceding later dunes look like thrusts. One may sort this out, by looking at fractures- and not the cross-bedding. I take it that parallel fractures (three or more) are not inter-dunal intervals, and these were noted in the report for Ebby’s Landing. Coastal dunes are voluminous in the cliffs, and even occur in the island interior; one such is on the east side of East Harbor drive, near Sands Lane- falling continuously on the shoulder. Some of the photos above may appear as cross-bedding glimpses. But the buckles are undeniably due to compression and thrusting. The question remaining is: since these buckles are very near the bottom of Till, this should strongly suggest that glacial sliding from the north has produced them.
Notice the one layer which is buckled, with the bed riding over itself to the north (all of these photos and comments are for beaches running north to south, on the west side of the island). This is opposite what should occur, for a glacial sliding over the upper layer causing thrusting toward the south. Rather, it appears that the force has come from below, forcing the bed to ride over itself.
Adding to all this mix, one photo shows that there are orthogonal fractures, running E-W in the cliffs. This would occur with breakage perpendicular to the dominant stress- which was N-S for the mid-glacial period (not the latest). Although not conclusive, this throws the argument to the side of glaciers being the dominant entity in this 50k ybp time.

Earthlore Magazine

EARTH LORE Magazine- a weekly Blog of True tales of the WEST and its Earth Science. Local earth happenings are shown, with photos, how the Blue Planet reacts to MAN's desecrations and FIGHTS BACK (on its own terms, and its own time schedule).

Weekly Renditions are made by the following Contributors:

Penny Scholten, geologist and outdoorswoman;
Dr. Chris Oravec, English at heart;
Harold L. Overton- earth critic and scientist; and
Col. Glenn Wasson, a Robert Service devotee’

English Subtleties (not Sub-Titles!)
A Turkish friend recited to me that even though she had a PhD in English, she still could not easily distinguish between the sounds Leather, Leader, Ladder, Let Ηer, and Lather. Those of us associating with the Ideas behind the sounds have no difficulty, but this illustrates the chore of getting Meaning from sound (with special difficulty for homonyms and synonyms). The following limerick emphasizes the closeness and subtleties in similar sounds in the English language which widely diverge in meaning.

My Rain, Maurine, lies Mainly on the Moraine

Although I was hardly a marine
Raising Merinos was no Mean
Task, for an uninitiated Teen.

I would promptly rise at Dawn
Performing duties, any Moron’d
Smilingly have a daily Go-On.

Wiping off the fresh Meringue,
Barely hearing the Daily Harangue,
Merry-No! while I watched the Gang.

I would longingly gawk Marina,
Keeping my thoughts on the Antenna
For the Lead in my Radio-Galena.

I have progressed from Merry-No
Earning my ring from the U of O,
To studies of the ol’elevated Colorado.

The Plateau, with its high Moraines-
Stoutly above the Western plains-
Is now the object of all my Brains.

Scarcely the same as ol’ Grey Mare, eh-NO?
Gladly the Cross-Eyed Bear- OH!
To forfeit the theme for this Spanish Merino.

You can see the trend for “some Mo’rain”
Is easily corrupted- causing Pain
For any (late) Verbalizer- on the wane.

Harold L. Overton

Klootchman (Lateral Moraine) Rock shows retreat of previous Glacial wall

Penn Cove, Whidbey Island

Rocky Point (Oak Harbor) floating Metasediments

Anomalous Rocks on Whidbey Island
WI is mostly covered with young glacial layers- mainly till and stream wash deposited in the last 50,000 years. Occasionally, there are outcrops of older rocks, such as at the Deception Pass area, just near the bridge, and surrounding the hiway 20. These rocks are named Metasediments (sediments which have been metamorphosed- squeezed at depth), and they are from the Mesozoic Era and older which outcrop regularly to the north and on the San Juan Islands. This means that they are older than 65 m.y. (Cretaceous and older), compared to the rest of the island- which is no more than ¼ million years of age.
A small outcrop of these older rocks occurs anomalously at Rocky Point- which is a section of west beach, on the Naval Reservation, in Section 21 T33N R1E (anomalously in the sense that they are surrounded by very young glacial Pre-Stone with age less than one million years)- see the above photos. The stone has been shoved up and laterally by shearing in the earth- the metasediments are being carried between two faults running about 120 degrees from north (almost SE-NW). This means that they are dragged by shear similar to that which caused them to be metamorphosed in the first place. The important questions to be asked here are as follows:
1. How and Why are the rocks being forced to the surface, when the only obvious movement anywhere nearby was that at the Deception Pass, where the continental hard rocks have been shoved almost due west, referenced to the Pacific plate rocks? Incidentally, this large faulting with several thrusts has created the San Juan Islands (in layers stacked on top of each other-but out of regular sequence), and the fault surface can be seen just outside of DP Park on the east side (where a E-W vertical wall or scarp occurs).
2. How can these heavy rocks (relative to the light weight till) be floating at the surface of the earth; if anything, they should at least sink in the soft sediments surrounding them?
3. How can we be sure that the metasediments are not connected with similar stone at their base? We can see that they protrude into the air, and are obviously disconnected on the north and south sides- but there is one side unseen and not open to inspection- the bottom. Why could not the metasediments curve upward from a near horizontal position deep in the earth and gradually bend and protrude vertically?

Analysis from the Photos
First, if these layers are being dragged along a 120 degree fault plane or shear surface on the south side (and the LIDAR map shows this clearly as a fault), then they cannot be connected to the original basement there. This means that the beds, if they are curving upward to a vertical expression, cannot curve upward from the south- since this is the discontinuous side. The fault plane on the north side would tell the same story, but this fault is not shown on the LIDAR map. This fault is only seen in the cliffs at the northern contact with the glacial deposits, and this is the weakest part of the analysis.
Second, the outcrop has a visible fracture running about NW-SE in one of the photos. This is seen as a large break in the rock with vegetation, a cavity, fractures, and seepage. This has remained damp over the 10 years I have visited it. The entire outcrop, which is about ½ km from north to south, has vertical bedding consistently oriented toward the 120 degree direction (which is the orientation of the LIDAR fault). It seems reasonable that the fault is left lateral, which results in the outcrop jutting into the sea on the north side, since all faulting measured by me for the north side of the island are left-lateral (2 cases). There are no other vertical beds anywhere on the island- even at Deception Pass. The NW fracture is the type occurring now on the island, and this indicates that the outcrops occurred first.
Thirdly, Rocky point is some 8 km or more from similar rock at Deception Pass, and not likely to be connected in the basement. There are the Silver Creek and Mariner’s Cove faults which I have inspected, which intervene in that distance. There is nothing nearby which indicates a connection- Rocky Point is anomalous! We still haven’t proved that Rocky point metasediments are not connected in the basement (subsurface) with others of its type, on the north side. But I hope to show the larger picture for Whidbey Island- to indicate that small events may sometimes be rationalized by looking at what happens regularly nearby.

CONCLUSIONS;1. The Rocky Point outcrop is anomalous, in that it is not connected with anything near at the surface- it is Mesozoic or older, contains metamorphosed sediments (metasediments), it is oriented in a direction of bedding pointing 120 degree from north, and it is faulted at least on the south side by a similarly-oriented fault as seen by LIDAR mapping.
2. The RP outcrop is surrounded on the ground surface by young, soft Till and non-indurated or non-strongly cemented sediments- it is anomalous in terms of strength, position, and orientation (except for the parallel faulting on the south side).
3. RP is a true point, meaning that it is resistant to storm erosion and juts into the Sound. It is increasingly covered by storm wash, as noticed for the ten years I have observed it (the sea is rising near 1 mm/year as measured by an independent geologist, near Admiralty Head).
4. RP is fractured in its mid-section by a NW-SE, or thereabouts, opening- which has an obvious accompanying seepage. This rock is the highest of those remaining- indicating that it is being shoved upward from below (which would be a reason why the metasediments are floating). If this is correct, then it is connected with the basement in some way- but not necessarily with the original neighboring metasediments.
5. Since the entire outcrop aligns in the common direction (120 degrees from north of ½ km aligned rock) it is likely that it is a separate block broken off from the original bedrock and carried along the active shearing zone. It must be sitting on top of other basement- with a low probability that it is connected with its original neighboring rock.
6. The orientation of 120 degrees from north, when extrapolated to the east side of the island is coincident with the location of Eerkes spring (which creates road breakage and can be found by looking for patches and a low place in the pavement on Torpedo Road, just NE of the Naval Commissary). IF these are connected in the subsurface, this indicates that the Rocky Point fault is of great significance. The orientation would connect with an obvious large and active fault at Utsalady Point on Camano Island, which can be seen on LIDAR decisively.

Whidbey Island Cliff Evidence of Violent Earthquakes

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Association of Faulting and Earthquakes

Earthquakes on Whidbey Island
Although W.I. is a young island, composed of mostly glacial Till (consequently dampening a lot of shaking by underlying Earth crust), it nevertheless has experienced some violent quakes. These are shown in accompanying photos, as evidence of what has happened in the past.
An attempt has been made to determine the frequency of quakes, from the time-spacing (vertically-separated layers) of obvious disruptions in the cliffs along the beach. The beach is almost the only place where earth movements can be assessed, since most of the island is covered by vegetation, rubble from glaciation, and water in ponds, creeks, and lakes.
The western beaches and cliffs are the ones which are cleaned by yearly storms, so that these should be relied upon as most revealing. These cliffs are sheared by slumping caused by storms and quakes, so that each year fresh views are presented. The evidence seen last year is later removed, so that a motion picture in one’s mind is made of a part of the layers as they retreat from one photo to the next. This amounts to as much as one foot yearly, and the conclusions reached in previous years can be tested for those scenes found NOW.
The accompanying photos, either at the top of the text or on ones following and preceding are from the Ledgewood portion of W.I., where the first location of a massive fault and its attending quakes can be found, along with the resulting house collapse. The casual observer would proclaim that this is simply slumping, and indeed slumping is common near the beaches on the south and west sides of W.I. But the next inquiry should be: what caused the slumping, particularly in an area where it is not so common?
In this case, a slab of a garage up the hill has been checked, to find that the slab moved to the right relative to the house slab, as shown by bent nails connecting a 2x6 between them. This is a Left lateral fault- meaning that when one stands on either side of the fault, the opposing side is displaced to the left. The house owner might have thought that he was the Victim of Bad Fortune to have the most slumping in the neighborhood, but he happened to have built his house on the fault line- where slumping is pronounced. You can see that the houseowner on the cliffs eventually capitulated! Cliffs and houses on the east side of Puget Sound islands are much less affected by winter storms, which carry away the fault and slumping debris. This feature requires the analyst to take information primarily from the west side (even though faulting ocurs on all sides of the islands). A fault found near Mariner's Cove on the east near Silver Lake and Creek results in little visual evidence and much less slumping.
The second photo looks in the direction offshore, along the NW-SE faultline, and finds that a saddle occurs where Seattle Pacific College resides (between Admiralty Head and Camp Casey). This is an excellent example which shows that a saddle on a topographic map, or a visual sighting, can strongly indicate a fault line.

The Bird got in the Act!
As Luck would have it, as I was aligning my camera with the NW-SE orientation, a lusty Raven felt the Earth’s impulse, and acted on his own to signal to me (via squawking and pointing) that we were getting a signal from the Earth. Since I am under Edgar Allen Poe’s influence, I immediately undertook to explore, what was meant by the Lost Lenore, and that which was most visual just beneath my Camera Door! All of this, you understand, while receiving a cell phone call from the notorious Black (as the Raven) Bart, a.k.a. Glenn Wasson. I had forthwith to dispatch the Bart, giving the ebony bird precedence; the Raven was most accommodating.

The 2nd separate cliff photo above, in a preceding Blog, shows the actual evidence of violent quaking, as seen in large blocks of angular rock (actually Pre-stone from the same general area, within a kilometer), which have fallen into crevices opened up in the earth during an earthquake. These angular blocks were later entombed in the earth, with the crevices closing- for viewing in cliffs which are eroding now. I have seen these episodes in at least four different elevations above the sea, indicating that the cyclicity of earthquakes for Whidbey island is on the order of 40,000 years/4 incidents = 10k years per violent quake (those paroxysms which opened up the ground surface and allowed nearby blocks to fall into the crevices).