Collecting at Essroc Quarry in Southern Indiana
On April 29 the Kyana Geological Society had its (almost)
annual field trip to the
Essroc Cement Co. quarry in southern Indiana. The quarry is in the Jeffersonville
and North Vernon Formations, both Middle Devonian in age. It is, by far, the
largest quarry in the region. The open pit exceeds 1,000 acres! It is a very
shallow
quarry because the rock is used for the production of cement and mortar mix.
There is a full scale cement mill on the property. This quarry was opened
around
1880 and has been in continuous operation ever since.
The Essroc quarry is so large, they sub-leased part
of the older unused quarry to
Aggrock (now Hanson) to mine the coral zone and underlying Silurian Louisville
Limestone for aggregate. (It isn't suitable for cement.) Essentially we have
a
quarry within a quarry!"
1
Our group is given a specific area back several hundred feet from the highwall
for fossil collecting. We are collecting silificied fossils from the residual
soil
and from limestone that has been peeled up into piles by heavy equipment.
(The front end loader has tires nine-feet in diameter.)
2
Years ago, the quarry was famous for Phacops trilobites
and abundant
Orthospirifer brachiopods. These days the erosional surface is closer to the
top of the Jeffersonville Limestone and the Speed Limestone. Athyris
fultonensis,
Lepatena rhomboidalis, and Rhipidomella brachiopods; Hadrophyllum
orbignyi
(button coral) and Bordenia knappi (horn coral) are more common.
Scattered
occurrences of the resiudual Beechwood Limestone with its coral variety and
Ancyrocrinus spinosus crinoid grappling hook holdfasts are targets.
This trip yielded the usual suspects, along with some Callixylon newberryi
petrified wood, residual from the decayed New Albany Shale (above the North
Vernon Fm.). The 10 year old son of a member found a palm-size Coronura
trilobite pygidium in a piece of crushed limestone used as road metal. He
was
pleased with himself -- and dad was beaming!
We moved over to a second spot a few hundred yards from where we started.
There I took the most spectacular tumble in years, slipping on the dirt on
the toe
of a spoil pile. I saved the camera, but scraped my thigh from just below
my
pocket to just above my knee. Ouch! I think I saw stars -- Regulus, Arcturus
and
Betelgeuse to be sure. A few minutes later, I found a 6"diameter coiled
nautiloid!!!
3
I was able to extract it and will put it back together
(it is in just a few pieces)
when I get some free time. The 10 year old found part of a smaller coiled
nautiloid about 30' from mine. Later another member found a 12" specimen
-
less complete than mine, but very impressive. One of the members reduced
a boulder to take home an Elaeacrinus verneuili blastoid. The
father of the
boy found a loose one about the size of a large black olive. I brought one
two partial blastoids and the base of a crinoid cup -- they are slabs of
limestone going into the landscape -- not specimen quality.
We found some of the boulders had coelacanth teeth
of the species
Onychodus sigmoides. (This coelacanth had world-wide distribution
and
is known from complete specimens in Australia. Apparently they were like
giant - up to eight foot long - Moray eels!) One nice bright blue tooth I
found was extracted by another member. (I didn't have the energy to mess
with it, I was too sore.) Another tooth (illustrated here) was partially
weathered out of the rock curving like a claw, but its position makes
the use of a saw necessary.
4
5
6
All in all, tumble not withstanding, I had a good
trip. I gave a lot of specimens
to other collectors who plan to give them to teachers and for club grab bags.
I brought back a farly small number of specimens (for me) and some nice
rock for the landscape (water-sculpted limestone, flagstone and glacial pebbles
for my dry creekbed garden).
Alan Goldstein
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