Friday, October 8, 2010

Where in the West: Rose Spit, B.C., Canada

Rose Spit, with North Beach to the right and East Beach to the left.

The October Where in the West location was won by Ron Schott (no Schott rule was invoked) for finding Rose Spit, which forms the northeasternmost tip of Graham Island in the Queen Charlotte Islands of British Columbia, Canada, about 35 km NE of Massett. The area can be viewed anytime the weather is clear and anytime one happens to get on the wrong side of the plane from Anchorage to Seattle (the right or west side), which MOH and I did about a year and a half ago, while returning from the start of the Iditarod.
The linear, north-trending East Beach in the foreground, with North Beach's beach ridges beyond and to the west.

Howard won the geology portion of WITW by noting the beach, spit, beach ridges, salt marshes or brackish lagoons between the beach ridges. I can't swear to the nature of the water between the beach ridges, but brackish to salty seems likely. Howard raised the question of whether the beach ridges are actually cheniers, which are beach ridges deposited on tidal mud flats or "on an alluvial plain of silt, clay, or peat on prograding deltas or coastal plains." I haven't found any information about what the sand ridges at Rose Spit are deposited on, so will have to go with beach ridge for now.
Also seen at Rose Spit:
"dissipative beaches backed by prograding foredunes on North Beach; reflective cuspate cobble beaches with a sandy low tide terrace on NW Rose Spit; and multiple-barred beaches backed by migrating foredunes and parabolic dunes on East Beach."
Pictures of these features — and much, much more — can be seen here, on page 3 and 4 of the pdf.

And from Overview of Geologic Hazards to Offshore Petroleum Development – British Columbia Continental Shelf:
"Megaripples, sand waves and sand ridges are particularly important in the vicinity of Rose Spit and Rose Bar at the northeast corner of Dogfish Bank. These features are the result of storm-driven sand motion on the shelf under the influence of topographic steering of tidal and wind-driven currents. In this area amplitudes of the sand waves and sand ridges can exceed 6 m. "
"The eastern coastline of Graham Island is largely dominated by a thick sequence of unconsolidated glacial outwash deposits capped locally by Holocene dunes. These sediments are retreating rapidly, with the eroded sediments being swept northwards towards Rose Spit. While average erosion rates apear to be about 1 m per year, retreat is highly episodic; in 1992-1993, for example, 11 m of land was lost at Cape Fife and 1.5 m was lost in a 24-hour period at the same site in 1994. Numerous, ephemeral shore-attached bars are associated with the high rates of longshore drift along eastern Graham Island. "
View Rose Spit at Flash Earth.

Some References:
Bornhold, B., and Harper, J., 2002, Overview of Geologic Hazards to Offshore Petroleum Development - British Columbia Continental Shelf, in BC Offshore Hydrocarbon Development, Report of the Scientific Review Panel (January 2002), Appendix 11.

Otvos, E., 2005, Cheniers, in M. Schwartz (Ed.), Encyclopedia of Coastal Science: Springer, p. 233-235.

Walker, I.J., and Barrie, J.V., 2006, Geomorphology and sea-level rise on one of Canada’s most ‘sensitive’ coasts: Northeast Graham Island, British Columbia: Journal of Coastal Research, SI 39.


Cath@VWXYNot? said...

Wow, what a cool shape!

I'd love to get up to the Charlottes (recently renamed Haida Gwaii, btw) for a kayaking adventure at some point. It's a major hassle (and very expensive) to get up there, but according to my former boss who went a few years ago it's totally worth it.

Cath@VWXYNot? said...

btw something on this page keeps crashing the Chrome browser. Firefox is doing better, but it's still acting weirdly. New widget?!

Silver Fox said...

Cath, I don't have any new widgets, and I'm not having any problem with either of those two browsers (or IE8), and Chrome is loading the page faster than the other two. It loads somewhat slowly in IE8 because of the new layout, but that layout is months old by now.

I did correct an error in the first picture, which was linking to a tag instead of the picture if you put your cursor over the picture.

The only thing new at all is the link to Flash Earth, which is just a link, so it doesn't seem like that would be a problem.

The kayak trip sounds like a great idea! :)

Silver Fox said...

I just commented using Chrome. It briefly said it was waiting for Google Analytics, which I don't think is posted on the sidebar.

Also, Chrome isn't showing two stat widgets, a map way below and the green widget below that.

Another newish thing is that on the main page, the last post has an embedded Google Maps iframe. Don't know if that could be a problem, but I'm still in Chrome without anything weird except the two widgets not showing.

Silver Fox said...

Now all widgets are showing in Chrome, so maybe those two are just slow. And the embedded iframe location on the post at the bottom of the page is showing alright.