Thursday, June 21, 2007
Whidbey- the "Soft" Island, compared to the San Juans
This Temporary Island
“Every Island is manned” could be the Logo for Whidbey and other significant Puget Sound Islands, since all of these water-surrounded bits of terra firma are considered refuges for some portion of society- due to the desire to escape from the problems of everyone else. An island represents a kind of Nirvana, where man can feel that he is distant from the artificialities of his culture. After all, there is sufficient water, agriculture land, and game to survive temporarily any artifice or arbitrary creation which the “others” can originate. He can feel “Free” to live by his own code, and indeed Whidbey seems to have many of these escapist subcultures.
Although Whidbey was named by the English sea captain Vancouver, it was actually first noticed by the Spanish explorers, after being manned by pre-historic Asians for some few thousands of years (Spanish nomenclature is still in use for some of the locations, e.g. San Juan de Fuca, Lopez, Port Angeles, and Sucia). Native middens can be seen today on some protected shorelines, which exhibit shells and artifacts discarded by ancient cultures. The mussel and clam shells were thrown down by the midden shuckers with their concave side up- where the meat was scraped and the residual shell was dropped from that meat-side-up position. A historic culture still resided on part of the island, near Coupeville and Penn Cove- called Salish at Snakelum Point, after the arrival of Caucasians. A backwater protective cove also exists at the end of Monroe Landing Road, where natives docked their canoes for protection from the winter storms. There is a peninsula at the same location (probably man-made), which blocked the SW winds from their idle canoes. Penn Cove runs counter to the normal north-south waterways about the island, since it exhibits a movement of an ice lobe (one of the last) which moved at an angle of 250 degrees from north- unlike the other glacial movements which generally moved south, leaving great scrapes and waterways on most of the island. With this abnormal movement of the ice (evidently downhill from such mountains as Glacier Peak) one can see features not noticeable on the other parts of the island- which generally are exhibited along a north-south axis. One can look into ancient canyons from fossil waterways along this E-W excursion, which are now filled with gravels and river-brought debris.
I have generally noticed that the western beaches and coastline of Whidbey Island recede yearly, so I undertook to measure the annual retreat. This was most noticeable, for the case of a newly built house near Ledgewood. Since I was there for its inception, I noticed over the period of ten years the amount of movement of the high tide line eastward. This was abnormal, since the lot owner disturbed the normal erosion of the beach. He undertook to place hewn granite stairs on the slope for easy access to the beach. In addition, he placed large boulders to block the sea’s advance. After the first year of emplacement, all trees had been uprooted and the stairs had been moved to the east by winter storms. There was about a three foot retreat of the cliffs, even with the boulder reinforcement. The operator had a good budget, and reset the boulder line to match the new beachhead, presenting an obvious recess into the cliffs, compared to his neighbors. Over seven years, his arrangement has now created a seven foot “bay” compared to neighbors’ coastlines, and he has a somewhat stable beachfront. The stairs mostly became covered by sand, but he has retrieved some of these to be emplaced further to the east, and now he has only to wait for the neighbor’s coastline to catch up with his accelerated erosion.
Finding an average erosion of the west beaches requires a measurement of the movement of old trees, where the trunks can be seen to partly slant (over the previous cliffs as the cliffs slumped). Looking at trees which are over the age of thirty years, one can see where they have leaned over the cliffs and then restarted to grow vertically. Using the diameter of existing two-angle slanted trees, and the fact that the whole tree would have leaned over the cliff at the time of slumping, one can calculate the rate of erosion. Measure the distance from the cliff face now to the tree base for the distance that slumping has proceeded since the tree leaned over the cliff (due to slumping). Then estimate the age of the vertical portion of the tree above the slanted portion, which determines the number of years since the last slumping. Assuming that slumping proceeds at the same rate as cliff retreat, the rate of retreat may be calculated: 12 feet/18 years yields 8 inches retreat yearly. There were two different trees which calculated this annual retreat, and the number may be considered useful for that particular location. However, the nearby location of a spit, point, bay, or other feature has a large bearing on the annual erosion by storms, so that one must consider aggravating features for any particular location. My opinion is that after watching Baby and Smith Island- just offshore from Whidbey- erode rapidly, that the main part of the island will wash into the Puget Sound within 1000 years. One can relate this to the width of channels between Whidbey and the Olympic peninsula (or to separation from Camano island or the Washington mainland), and speculate that these channels have been created by NW-SE faulting in the 14,000 years since the last glaciation. These distances approximate the width of Whidbey, and this gives some confidence to the calculation of annual retreat.
This average annual retreat of Whidbey’s western coastline is somewhat less than a foot yearly, so give yourself a foot of insulation from the sea for each expected year of your remaining life, to remain HIGH and DRY!