Newspaper article The Florida Times Union

Behold the Dunes, Nature's Stately Castles

Newspaper article The Florida Times Union

Behold the Dunes, Nature's Stately Castles

Article excerpt

Sand dunes come in five types. That news came to me from an

article in the June issue of Backpacker. I have delayed this

column awaiting a judgment on the success of our "new" beach.

Star dunes are the ones found in the Sahara, where they can

reach 250 feet in a random series of peaks. Transverse and

parabolic dunes are coastal types distinguished by patterns of

prevailing winds. Brachan dunes are crescent-shaped with tips

pointing downwind because of only one wind direction.

Longitudinal dunes are found in areas of limited sand and form

in parallel lines from prevailing winds.

Dunes range up to more than 800 feet long and are found the

world over and even next to mountain ranges. Sand is the result

of rock reduced to individual mineral grains by wind and water

erosion.

My four columns on our local sands spoke of the origins of our

heavy mineral sands deposits. Most of our beach sands formed

about 125,000 years ago, after the last Ice Age when the area

known as North Carolina was eroded into the ocean and deposited

as Florida.

Most of our sand is quartz, silica dioxide, but the most exotic

minerals include three forms of titanium dioxide -- two with

iron -- zircon silicate, and monazite. Our sand is actually

made up of 31 minerals.

The once high and plentiful dunes stretching from Regency Square

to Baymeadows were the unnatural piles of leftover quartz sands

from the titanium mining operation that ended in the early '60s.

Deposits of heavy mineral sands sit under the homes on Amelia

and Hilton Head islands.

I waited until now to see what winter storms would do to the new

beach. We have had fewer northeasters than expected for the

past two winters. So far the beach is holding well. Areas for

about a half-mile in southern Atlantic Beach and again starting

about 15th Avenue South in Jacksonville Beach usually lose sand

sooner than the rest of the beaches. …

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