Gulf Coast Pure Quartz Sand

On a recent trip to Pensacola Beach, I was amazed at how truly white the sands are on this stretch of the Gulf Coast.  I grew up on the light ruddy brown sand beaches of southern California, refreshed as they are from the crystalline rocks of the Transverse and Peninsula Rages, until recently (geologically speaking) sand delivery was somewhat hampered by flood control efforts.  I now live near the shore of the gray sand beaches of Puget Sound, supplied nonstop by eroding bluffs of glacial outwash sands.  The sands of the Gulf Coast beaches were formed from the wearing down of the Appalachian Mountains, which began their rise some 480 million years ago.  The Gulf of Mexico opened up some 300 million years ago.  The rivers in this neighborhood stopped bringing sand some tens of thousands of years ago.  In sort of a reverse of the Bowen's reaction series, the other mineral grains (e.g. olivines, pyroxenes, amphiboles, mics, and feldspars) weathered and wore down to miniscule particles leaving the highly resistant quartz grains.  This reversal is known as the Goldich dissolution series.  The sand here is almost pure quartz, blindingly white when massed as an endless Gulf Coast beach.

I did see some Deep Horizon oil spill cleanup crews patrolling the beaches in ATVs and just offshore in small skiffs.  I didn't see any evidence of oil spill during my brief beach walks.  I'm sure the oil is out there somewhere lurking.

Fall: On the Beach

It's fall and the Heerman's gulls again make their contrarian fall migration northward from Baja California to our local beaches and elsewhere along the northern Pacific coastline.  Other gulls are here, too, but my identification skills with the other gull species are not so good, especially with the juvenile phases and subtle seasonal variations.  The American widgeons are here and later in the winter we'll see other ducks, the red-breasted mergansers and the goldeneyes, common and Barrows.

I encountered several beached lion's mane jellyfish (Cyanea capillata), the largest known species of jellyfish.  Jellyfish usually die off this time of year as their food supply of plankton dwindles.

Harbor seals are the most abundant marine mammal in Puget Sound.  Harbor seal pups can be found on the beach in the late summer and fall, resting as mother forages.  People may come across a seal pup on the beach and think it is abandoned but it is not.  The pups must not be disturbed.  Seal Sitters is a volunteer group dedicated to the protection of marine mammals in the urban environment along Puget Sound.  I came across a Seal Pup last year but this year I came across one that was unfortunately dead.  Seal pup mortality is relatively high as I understand.