Wednesday, February 08, 2006

Coquina Stone


F
L
Rocks









This stone is a cut block of Coquina. It is a natural sedimentary rock that forms along the east coast of Florida. We are rock-challenged in Florida. There's sand everywhere, but real rocks are mostly limited to chalky limestone of various grades and this unique shellstone.

Coquina forms in the general sedimentary way, layers of sediments deposited atop each other and eventually being squeezed into a rock. (Remember 8th grade Earth Science?)

In the case of coquina, you have the additional "glue" of the lime from the seashells leaching out and naturally cementing the shell fragments together. Most of the shells in coquina rock are the remains of the coquina clam ...genus Donax. There are huge deposits of coquina along the coast and in a few places, the surf has exposed the rock to provide us with a truly rare event in Florida...a natural rocky beach. Posted by Picasa

14 comments:

Laura said...

Thanks for the photos and info about the Tabby walls. Those buildings that are still standing from the 1700's, could they be our answer to hurricane code? ;)

You're right about being rock challenged in Florida. Have you been to Hutchinson Island on the east coast, near Stuart?
In particular, I was thinking of the "House of Refugees" that sits along the beach there. The reason I mention it is because that's where I lost almost half a toe from climbing on the rocks, and where, on another occassion, my brother almost lost HIS toe from just walking along the shore! There are giant boulders along that stretch, rare for Florida beaches.

Then of course, there's Miami with it's coral rock, which makes it hard to dig in the soil.

When I lived in North Fla, however...it was all sand and clay and narry a rock in site. I really don't miss that clay for some reason. ;)

Interesting, digging in the soil where I live now (tampa bay area), it is all sand and loaded with tiny shells. not a rock in sight.

Thunder Dave said...

Nice bit of history and geography! I agree with Laura, it's kind of funny how the naturally generated building material seems to last longer than the man made stuff!

Just for the record: Ohio is rich with rocks. If you put shovel to earth you can usually get about 4 to six inches of dirt/clay and then "clunk", another rock.

The MacBean Gene said...

Groundhog Mountain rocks! Within several hundred feet of our house can be found granite, quartz, slate, shale as well as some others I'm not sure of. Put a shovel in the ground, hit a rock. This area is a geologists dream.

Hick said...

Rocks? You don't need no stinkin' rocks.

Coincidentally enough...Nerd Boy is studying geology in his 7th grade earth science book. (We just read about sed. rock formations on Monday.) I'll have him take a looksee at your post along with the one below. You are making my lesson plans easy.

So I guess it's true: "Necessity is the mother of invention" when it came to the first settlers of your area.

pablo said...

I have one of these rocks. It is smaller and looks something like a biscuit. I've found that if you soak it in milk long enuf and had a whole lot of honey, it doesn't taste all that bad. A little crunchy, and you need something to wash it down, but a novel experience nonetheless.

OldHorsetailSnake said...

You are just full of interesting stuff. Thanks a bunch.

(I FINALLY got you linked on my page. I am so slow.)

Floridacracker said...

Laura,
When the kids were little, Hutchinson Island was a favorite summer retreat. We always hit Bathtub Beach which was protected by a worm rock reef. Neat place!


Thunder,
We would like to hit a rock once in awhile.


Mac,
Rock envy here.


Hick,
Definitely on the necessity thing. Nerd boy could google DONAX, COQUINA, THE ANASTASIA FORMATION, for some more info. I don't think any of those would bring up naughty sites, but you better look over his shoulder just in case.

Pablo,
I have never tasted coquina, but now feel compelled to. How odd you would have such a stone so far from mother ocean.

Hoss,
I'm trying. I'm down to rocks and dirt now :)

Abandoned in Pasadena said...

I have a coquina rock and I never knew that there were coquina clams...very interesting.

I will have to look the clams up to see what they look like.

Floridacracker said...

Abandoned,
They are beautiful, multicolored and shaped like little wedges. Only about the size of your fingernail.

vicki said...

okay. now here Michigan is one up on Florida. We have many and beautiful stones and rocks. Quartz and slate and granite and so many lovely agates. Best of all we have something called Isle Royale greenstone and Petoskey stones. Let me know if you would like some samples...

Xariklea said...

Isn't the old fort in St. Augustine made out of coquina rock? I love it up there...I wish I'd gotten the job with Flagler College all those years ago!

When I was little, we used to dig up coquinas by the bucketfuls and make a soup out of them....

Floridacracker said...

Vicki,
It's true, we can't compete with MI when it comes to rock variety. I've been envious since reading Rascal as a kid. I remember descriptions of beach agates along the lake shore.

Xariklea,
Yes it is. The photo was actually taken on the fort grounds.
I've heard of making a soup from coquina clams, but never tried it.

doubleknot said...

You have taught this old Florida girl something new - or perhaps I had just forgotten about the Coquina rocks. Have had Coquina soup though. We live on the bay and have to go south to Coquina Beach - haven't had a chance to go there in a while though. Interesting about the Tabby rock also - something else I know I didn't know.

Floridacracker said...

Doubleknot,
I am going to have to make the coquina soup. Glad this was useful.