Saturday, May 12, 2012

Hope Island


 It's a short paddle from Ala Spit across to Hope Island, although there can be a lot of water moving through this passage, leading to some tricky rips and swirls.

AERIAL VIEW

The island is about a mile long and less than half a mile wide and is entirely managed as a Washington State Park (there's another Hope Island State Park in South Sound, just to keep things confusing).  There's a small primitive camping area on a protected cove (Langs Bay) on the north side - the camp sites are on a low bench that looks like it is several feet of shell midden sitting on several feet of clay.


The highlight of the island is the small 40' high promontory at the southeastern corner, which is connected to the main island by an isthmus that is part bedrock ridge and part tombolo.  Most of the rock appears to be serpentinite and some of the exposures are pretty complicated.  There's a wonderful gravel beach extending west along the southern shore - backed by serpentinite cliffs and a dense band of very large wood (a south facing beach north of the mouth of the Skagit is a natural trap for large wood).

The metamorphic bedrock on the island is mantled in some places with till or other Pleistocene materials. A small bluff at the northeast corner of the island displays a series of gravelly shell-rich beds - are these old beaches (but why so tilted?) or are they reworked deposits - sort of a shell-conglomerate or coquina?  To the south, there are even more complex deposits that include fossil shells.




3 comments:

Dan McShane said...

Not sure if these old beaches are uplifted or if they may be remnant emergent deposits. That said, this an area that likely has seen ongoing seismic uplift given its location along the Devil Mountain- North Whidbey Fault zone. A bit to the south Whidbey Formation delta silts are tilted at an angle of 20 degrees.
Thnaks for the writeup and I will have to paddle out there some day.

Gravel Beach said...

Here are some photos of what appears to be the same site - taken a decade earlier:
http://wa0uwh.blogspot.com/2011/12/island-of-shells-contd.html
(note this is the second of two posts - this has photos, the first has more narrative)

Gravel said...

Not sure if these old beaches are uplifted or if they may be remnant emergent deposits. That said, this an area that likely has seen ongoing seismic uplift given its location along the Devil Mountain- North Whidbey Fault zone