Thursday, November 24, 2011

Oooooooids

I have oolitic sand from the Great Salt Lake!  And Brine Shrimp eggs- finally.  (Thanks Wendy!)  I hope they hatch.  Actually when I went to the lake a few weeks ago and got a bunch of the brown 'organic material' I'm sure that does have Brine Shrimp eggs in it too.  Just wasn't sure how to go about isolating and growing them.  This time the ranger just put a couple pinches of eggs in my container of water for me since there still weren't any live shrimp.

Ooids / Oolitic sand
Regular beach sand- most of it- is made out of quartz, and if you look closely at it, it's a bunch of angular fragments of the mineral.
Oolitic sand, on the other hand, is made up of tiny spheres.  No kidding, so freaking awesome.  And because of this, by the way, the sand is very soft.  These sand grains are made of calcium carbonate (the ingredient of limestone), which have adhered to some tiny speck of something or other (kinda like moisture condensing around a particle of sand to form clouds).  The center of these spheres is often Brine Shrimp poop actually. :)  Lovely isn't it?  An entire beach full of shrimp poop.  It boggles the mind.  So, calcium carbonate that was in solution in the lake (Lake Bonneville), would precipitate onto these little pieces of excrement, and get rolled around by the shallow waves, creating the little spheres.  Another interesting difference to note is that quartz and other sands are formed by the break down of larger rocks.  But ooids start smaller and are built up.  (See http://www.sandatlas.org/2011/11/ooid-sand/)  Pretty cool.
Also the water would have had to be warm, because warm water can't hold as much dissolved Carbon Dioxide.  This fact would help lead to the precipitation of the calcium carbonate onto the poopy nuclei.  So this tells us that Lake Bonneville would have been warm (at some point) and pretty windy.

I got mine from Antelope Island today.  Don't know why I didn't get sand from the other areas I went to a month ago, but whatever.  I'll go there again some day and collect stuff.

Antelope Island has a lot of really cool Tintic Quartzite.  At the top of Buffalo Point, it's a natural playground.  My kids had a blast running around climbing on the big rocks. :)
Tintic quartzite at Buffalo Point, Antelope Island State Park

Halite was a bust though, there wasn't any in that area.  Our ranger guide suggested trying the north end of the lake to try to find some of that.  We didn't have time this time so I'll do some more research to make sure I can get it before I attempt to go get any- it's quite the long drive.

Lake Bonneville
The Great Salt Lake is a remnant of the ancient Lake Bonneville which covered most of Utah from about 30,000 years ago until 14,500 years ago when the great Bonneville Flood happened, lowering the level of the lake drastically.  As it continued to drop, all these shorelines were formed, top to bottom- oldest to youngest.  (See http://geology.utah.gov/utahgeo/gsl/flash/lb_flash.htm ).  From Buffalo Point on Antelope Island, looking across White Rock Bay, you can see the 4 shorelines very well, as labeled here.
Lake Bonneville ancient shorelines as seen from Buffalo Point on Antelope Island, Great Salt Lake, Utah

Biology:
Beach of Great Salt Lake
The beach we went to had a lot of black deposits on it which turned out to be brine fly pupa cases.  When the flies are developing, they go from a larval state to a pupa, then they emerge as flies, leaving the case behind.  The amount of these cases littering the beach was pretty incredible.
Brine Fly pupa cases on shore of Great Salt Lake



Brine Shrimp lay cysts when the weather is cold, so these were all over the beach as well, but they're so small it's hard to find them and be able to say that's Brine Shrimp eggs.  Brine Shrimp are pretty amazing.  When the weather is cold, they lay the cysts/ eggs.  But if the weather is nice, they can also actually give live birth!  They can choose either one based on the climate that year.
Brine Flies and Brine Shrimp are the only things that live in the Great Salt Lake, because it is so salty.  South of the causeway where we were (Stansbury Bay) is twice as salty as the ocean, and the north side is 4-6 times as salty as the ocean!  There were definitely a lot of birds visiting and probably eating the flies and shrimp.  It's a good place for flocks of migrating birds to stop for a meal.  We also saw a couple of really neat birds of prey on the island.  Some type of hawk I suppose, but I'm not sure, it wouldn't hold still for me to get a good picture.
And I noticed some areas of thick growths of Fragmites everywhere.  This is a pretty invasive plant because it grows really dense and tall (we saw some about 8 feet tall, pictured below), making beach areas not as nice for various living creatures trying to use the area, and it competes with native plants.
Fragmites at Great Salt Lake

It was another awesome outing learning about the amazing world we live in.  I love living in Utah, there are so many way cool things to see and learn about. :)

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