Lynn Scheu relayed a question from a Texan: "When I was a kid in Galveston,
we had many oystershell sidewalks but they disappeared with the 1960's. What
happened?"

I think that they may have been paved over. Shells of estuarine bivalves,
Eastern Oyster (Crassostrea virginica) and Common Rangia (Rangia cuneata)
occur in vast numbers on the US Gulf Coast, and were commonly used for
roads, driveways, etc. In Mobile Bay (Alabama) and  Lake Ponchartrain
(Louisiana), big dredges worked one area after another for many years until
the deposits of dead shells (buried "oyster reefs", really sandy shell and
sandy mud and not all composed of oysters) were mined out.

One oddity of Rangia cuneata is that the clams grow to their largest size in
slightly brackish water that is too fresh for them to allow them to
reproduce. Evidently they live well in almost fresh water, but require a
higher salinity to have young (Tarver & Dugas, 1973).

If you're ever in coastal Alabama, be sure to travel along Old Shell Road
from downtown Mobile out to Spring Hill. The two-lane road passes through a
variety of neighborhoods from poor to rich, and the older part is shaded by
live oaks. The road was originally paved with shell, but of course has long
been paved over with asphalt. Needless to say, none of these delights are
visible from the interstate highway.

A stranger material was used in downtown Mobile in the nineteenth century:
brick-sized blocks of wood, which were easy on horses' hooves. Where the
asphalt has worn thin, you can still see the wooden blocks, now almost
black, here and there.

But to return to Rangia, I am curious about the best way to pronounce the
word. I always pronounced it as "range-ia" with a soft g, but then learned
that the name honors a man by the name of Rang, pronounced "rahng". It's not
much of an honor if people consistently mispronounce your name in genus
form, so maybe we should say "rahng-ia" instead of "range-ia", but it's hard
to change old bad habits! Maybe we should split the difference and know that
we always call it "wrong-ia".

Andrew K. Rindsberg
Geological Survey of Alabama

++++++++++
References

For oyster shell dredging in Mobile Bay, Alabama, see:

Chermock, R. L., 1974, The environment of offshore and estuarine Alabama:
Geological Survey of Alabama, Information Series 51, 135 pp. See p. 120-121.

May, E. B., 1971, A survey of the oyster and oyster shell resources of
Alabama: Alabama Marine Resources Bulletin 4, 51 pp.

Ecology and dredging of Rangia in Lake Ponchartrain, Louisiana:

Fairbanks, L. D., 1963, Biodemographic studies of the clam Rangia cuneata
Gray: Tulane Studies in Zoology, 10(1): 3-47.

Tarver, J. W., and Dugas, R. J., 1973, A study of the clam, Rangia cuneata,
in Lake Ponchartrain and Lake Maurepas, Louisiana: Louisiana Wild Life and
Fisheries Commission, Oyster, Water Bottoms and Seafoods Division, Technical
Bulletin 5, 97 pp.

Oyster use in Texas:

Gunter, Gordon, 1972, Use of dead reef shell and its relation to estuarine
conservation: 37th North American Wildlife and Natural Resources Conference
(Washington, 1972), Transactions, p. 110-121.