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7 Souvenirs of August

EarthCache

Claybanks-What's Preserved in Stone?

A cache by lagrac
Hidden : 4/20/2013
In Iowa, United States
Difficulty:
3 out of 5
Terrain:
3.5 out of 5

Size: Size: other (other)

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Geocache Description:

Developing an integral understanding of Earth history is basic to a complete knowledge of Iowa geology.
Iowa's rocks record a geologic history that goes back almost
3 billion years.

The Devonian Period.

Warm, shallow seas covered Iowa during Devonian time (345-395 million years ago).
These waters were home to numerous marine invertebrates including brachiopods, gastropods, stromatoporoids, and pelecypods (just to name a few).
 photo pelecypods1_zps7d90a68f.jpg  photo brachiopods_zps7ce39fc2.jpg  photo gastropods_zps2e7fd9b2.jpg  photo stromatoporoids_zps63a6b2f4.jpg
Sediments from this time are present at Claybanks Preserve in the form of various rock layers.
The name “Claybanks” refers to the light-colored soft limey shales of the 375-million-year-old rocks bearing the fossils. These outcrops of soft shale and limestone found along the banks of the Winnebago River (originally called Lime Creek) are where the “Lime Creek Formation” was first described in the geologic literature and thus represent the “type-locality” for this formation.
The Lime Creek Formation is divided into three members: Juniper Hill, Cerro Gordo, and Owen.
The relatively soft limestones and shales of the Cerro Gordo and overlying Owen Members are exposed here, and the abundant fossils within these layers comprise the famous Lime Creek Fauna.
This unit is regarded as one of the premier fossil collecting beds in the United States.
Fossils naturally weather free from the shales and limestone every year.

Unlike other preserves...
the collecting of fossils is allowed at Claybanks.

Here is your chance to apply what you have learned
and have some fun.


To receive credit for this EarthCache:

Visit Claybanks and find yourself a fossil.
(This EarthCache's posted coordinates are a good place to start your search, but based on personal experience, you can find them almost anywhere along the river.)
Using the pictures above, identify it.
Describe what you found in you log.
(What type of fossil is it, what size is it, what colour is it, etc)

And, in an e-mail to me. Answer the following questions.

1. The Lime Creek Formation is divided into three members.
Which of these three are not exposed at Claybanks?

2. Northeast Iowa seems like a strange place to find invertebrate fossils.
What does their presence here tell you about this area's geologic past?

I would like to thank John Pearson of the Iowa DNR for granting me permission
to develop this EarthCache here.


 photo OfficialECBanner650.jpg

Additional Hints (Decrypt)

Gur yrns yvggre fuebhqf jung lbh frrx.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)

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Find...

10 Logged Visits

Found it 8     Write note 1     Publish Listing 1     

View Logbook | View the Image Gallery of 15 images

**Warning! Spoilers may be included in the descriptions or links.

Current Time:
Last Updated: on 4/6/2014 4:15:59 PM Pacific Daylight Time (11:15 PM GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum