Crawfordsville Crinoids EarthCache
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This Earthcache requires a short hike along a rail trail, including
a somewhat steep ascent and descent on each end. The trail is a
converted railroad bed.
CRAWFORDSVILLE
CRINOIDS
Few places have contributed more to our understanding of fauna of
the Mississippian Period than the famous Crawfordsville crinoid
beds. Exquisite specimens of crinoids found in and around this
small Indiana town grace the collections of natural history museums
and universities all over the United States and abroad.
HISTORY
According to local legend, in 1842 the 9-year old son of Wabash
College professor Edmund Hovey returned home with a “petrified
toad” that he had found along Sugar Creek. His father recognized it
as the water-worn head of a fossilized crinoid. Professor Hovey
himself had noted the abundance of crinoid stem segments in the
valley as early as 1836, but no further crinoid heads were found
until 1851, when Wabash students found two well-preserved
specimens.
Local collectors D. A. Bassett and Orlando Corey began excavating
the bedrock rather than relying on locating fossils freed by
erosion. Their efforts yielded crinoids that had been preserved in
perfect detail with head, stem, and root system intact.
Professional and amateur fossil collectors began coming to
Crawfordsville in pursuit of their own valuable specimens. By the
1870s the sites excavated by Bassett and Corey on the north edge of
town were largely played out, but a number of other sites in the
surrounding area were identified and excavated well into the 20th
century.
WHAT ARE CRINOIDS?
Crinoids look like plants and are also called “sea lilies,” but
crinoids are in fact invertebrate marine animals of the phylum
Echinodermata. They are related to starfish and sea urchins. Direct
ancestors of the fossilized crinoids survive today, but these
simple creatures reached their peak in the Mississippian Period,
which is sometimes known as the “Age of Crinoids.” Although there
were many species of crinoids, they shared a basic morphology
consisting of a stem by which it anchored to the sea floor, a calyx
which enclosed soft body tissues, and arms which filtered food from
the water.
Crinoids were and are passive feeders that collect food particles
as current-driven water passes over their feathery arms. The fossil
record from Crawfordsville suggests that multiple species of
crinoids lived together in dense communities. Species often
differed in the length of their stem and the configuration of their
calyx and arms, and thus could live in the same space but occupy
different niches in the water column.
GEOLOGY
Crinoids thrived in the warm inland sea that covered the area
during the Mississippian Period some 340 million years ago. The
crinoids living near what is now Crawfordsville were established
near a delta system that periodically buried the colonies in silt.
This silt eventually hardened into stone that preserved the
Crawfordsville crinoids in glorious detail. In the 1960s Gary Lane
of the University of California at Berkeley made a careful analysis
of the stratigraphic occurrence of the Crawfordsville crinoids. His
study identifies the fossil-bearing stone of the famous Corey’s
Bluff site as siltstones and limestones of the Edwardsville Member
of the Muldraugh Formation. One reason Crawfordsville crinoids are
so desirable is because they are found in a siltstone matrix that
is soft enough to be removed without harming the fossil. This
enables the specimen to be revealed in bas relief or even in
3D.
LOGGING THIS EARTHCACHE
The primary goal of this Earthcache is to increase awareness of
Crawfordsville’s important place in the history of paleontology and
to allow cachers to participate in a small way in that
history.
The Corey’s Bluff and Bassett quarries are in private hands and are
closed to the public. The posted coordinates will take you instead
to a popular public access point on Sugar Creek where crinoid
fossils are easily found. Public parking is available nearby at the
Rock River Landing trail head just off Country Club Road west of
Crawfordsville. A short hike of approximately .3 miles along Sugar
Creek Trail will take you to a pedestrian bridge over the creek. At
the southwest end of the bridge is an unimproved trail leading down
to the creek bed (please use caution when descending this steep
trail; it can be slippery).
NOTE: This Earthcache may be inaccessible after heavy rains due
to flooding!
The gravel bank of Sugar Creek at this spot is very wide, and it
extends for nearly half a mile to the southwest. If you have an eye
for fossils, you will quickly spot bits and pieces of fossilized
fauna, including crinoids, corals, and the occasional brachiopod.
Since this cache is about Crawfordsville Crinoids, your task is to
find a crinoid fossil. Unfortunately, you will not find the
museum-quality specimens that made Crawfordsville famous among
paleontologists—those must be excavated from fossil-bearing strata
with heavy equipment. But small crinoid stem segments washed out by
the creek are abundant, and it is okay to save a few specimens as
keepsakes.
To take credit for this Earthcache you must do the following:
1. Find a crinoid fossil on the gravel bank.
2. Post two pictures:
a) a close-up of the crinoid fossil to establish the find
b) a picture of you or a team member displaying the fossil with the
trestle bridge in the background to prove the location of the find.
No need to show faces for those who prefer not to.
Please imitate these pictures by our team:
HAPPY FOSSIL HUNTING!
Additional Hints
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Treasures
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