Date: Thu, 28 Dec 2000 20:32:05 -0600
Reply-To: Conchologists of America List <CONCH-L@LISTSERV.UGA.EDU>
Sender: Conchologists of America List <CONCH-L@LISTSERV.UGA.EDU>
From: "Andrew K. Rindsberg" <arindsberg@GSA.STATE.AL.US>
Subject: Re: Fw: mollusca Long-lived mollusk question
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Paul Monfils asks how deepsea mollusks could lay down annual rings in a
virtually changeless environment. The problem lies not with the mollusks,
but with a long-standing misperception of deepsea conditions. True it is
that deepsea conditions are among the most constant on the planet, with
little annual variation in temperature, currents, and so on. But deep-sea
FOOD arrives as a gentle rain of bodies and fecal pellets from the upper
layers of the ocean. Since food production in the upper layers changes
dramatically during the year, so do the amount and kinds of food delivered
to the abyssal seafloor. Hence, deepsea clams can grow more quickly during
one season and annual rings are plausible.
In some shallow-water shells, assiduous ring-counters
("sclerochronologists") have found evidence of rings depending on tidal
cycles. They have even shown that Devonian corals record a year having about
400 days instead of the current 365. The physicists told us decades ago that
the moon must be very slowly retreating from the earth as the earth's day
slows down, since tides slow the earth down but angular momentum must be
conserved. Now we have proof that tidal slowing of the earth really happens.
Andrew K. Rindsberg
Geological Survey of Alabama
Tuscaloosa, Alabama, USA
P.S. I wasn't in Tuscaloosa during the recent tornado, a "floor-sweeper"
that traveled for about 18 miles (about 30 km) on the ground and killed 12
people, including the brother-in-law of a Survey staff member. Damage was
extensive in the southern outskirts of the city. The whirlwind traveled
within 1 km of my apartment, which was not touched. Radio and television
broadcast a warning about 18 minutes before residential areas were hit,
which is a relatively long warning for these events. Most people had time to
find shelter, if only an interior room.
One often hears of families that "lost everything" in a tornado and I've
always wondered how the physical destruction can be so complete when the
occupants of such houses often survive. Well, now I have some idea. I spoke
with another Survey employee who helped her son and daughter-in-law pick
through the debris of their home. Although some walls were left standing,
the house was so broken that they didn't dare enter parts of it. The
furniture was so broken that it wasn't worth saving. Clothing was either
shredded or filled with bits of glass. Canned goods were buried in the
remains of the kitchen. There just wasn't much left to salvage from the
homes that were hardest hit, even if the most interior room was less
damaged.
Needless to say, these people needed warm clothing as well as food and
shelter, and relief organizations needed cash in addition to contributions
of goods. The community response was immediate and terrific; donations
arrived from as far away as Washington State. But some people will be
rebuilding their lives long after the tornado is no longer news. This is a
fact of life, like many others.
Another little-reported aspect of disasters is the effect on house pets. An
animal shelter was in the path of the tornado, and although all the animals
survived, the poor things had to be rounded up afterward, terrified,
disoriented, and coated with wind-blown debris. I heard this directly from
another Survey staff member who volunteers for the shelter, but as far as I
can tell, this item didn't make the news.
Anyway, that's the news "behind the scenes" in Tuscaloosa. I'll be away from
the office till after New Year's Day. I hope that y'all had a happy Yule and
will find many wonderful shells in the coming year.
Andy
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