Nature and Science Programs at Wonder Works

ESCONI Juniors – 350 Million-Year-Old Fossil Sea Animals from Indiana
March 4, 2016, 5:40 am
Filed under: ESCONI, Fossils

We’ve been doing the Indiana Fossil Hunt activity for many years at ESCONI and elsewhere . Here’s some information about the fossils found in the “red dirt” that naturally dissolved from Indiana Limestone:

What are they?  These fossils are all that’s left of sea animals that lived a really long time ago.

How long ago?  Long before the earliest dinosaurs — about 350 million years ago.

What kinds of animals were they?  They were mostly sea animals that didn’t move very much, if at all, when they were alive.  The most common ones were:

Crinoids.  Broken stems of crinoids look like beads.  Crinoids are sometimes called sea lilies, but they are actually animals related to sea stars.
Horn corals.  These coral skeletons are shaped like cow horns.  Horn corals lived alone (like sea anemones), not in colonies (like most other corals).
Stick Corals.
Broken bits of stick corals look like hollow twigs, but they are made of rock.  Stick corals grew in bush-shaped colonies.
Skeletons of bryozoans are covered with pin-prick sized holes.  A tiny animal once lived in each hole.  Bryozoans are also called moss animals.

Where are the fossils from?  They were collected on a hill top in Southern Indiana (about 20 miles south of Bloomington).

How did they get there?  The hill is made out of limestone rock.  The fossils were originally part of the rock.  The rock at the very top of the hill gradually dissolved away over thousands of years.   All that was left behind was bits of rock, fossils, and reddish clay.

What’s limestone?  Limestone is a rock that’s often made of the skeletons of sea animals.  The limestone in that hill is the world famous Indiana Limestone.  Indiana Limestone is quarried and used as a building stone.

Where can I find Indiana Limestone?  Look at older buildings, especially those made of brick  The window sills (yellow arrow) on many older brick buildings are made of Indiana Limestone.  Also, if you ever go to the Maze Branch of the Oak Park Public Library, look closely at the front steps  — they’re made of Indiana Limestone!  You can even see tiny fossils in the steps.

Where can I learn more?  Follow these links:

   About Fossils:

See a drawing of the tiniest fossils in the Salem Limestone, called “microfossils.”  The Irving School window sills, and most of the Indiana Limestone used in buildings, is made of tiny fossils like these.  Bigger fossils, like the ones we collected, aren’t as common.
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Here’s a nicely written, short article about fossils in the limestone walls of a library at Harvard University:
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Here’s a Web page about fossil crinoids:
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Here’s a Web page about fossil corals:
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Here’s a Web page about fossil bryozoans:
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About Indiana Limestone:

See a drawing of an Indiana Limestone quarry:
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See a drawing of how they cut Indiana Limestone into building stones:
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Rock Collection Cards
March 4, 2016, 5:35 am
Filed under: ESCONI, Rock Hunters

At both the 2016 Forest Park Public Library STEAM Family Fair and the ESCONI Juniors booth, there were several types of rock collections that young collectors could make for free. (Only a few collections were available at any time.)

Collectors could take the rocks and a card home in a plastic bag. Scroll down this page for photos of completed cars and more information about the rocks


ROCKS FROM VOLCANOES: Pumice and Scoria are lava rocks that have lots of bubble holes. Apache Tears are solid lumps of Obsidian (volcanic glass).



ROCKS BY COLOR:  This collection card has rocks can be identified, in part, by their color:

Rock Hunters: Collection of rocks identified, in part, by color.

You can learn more about these rock types at the Neighborhood Rocks website. Here are direct links to five of the types of rocks shown above:


The following collections were only available at ESCONI:

ROCKS ARE MADE OF MINERALS:  This card was designed to show that many types of rocks are made of one or more types of minerals. The example on this card, pegmatite, includes three types of minerals: white mica, pink feldspar, and quartz:


Click here to learn more about pegmatite.


CLASSES OF ROCKS  The third type of rock collection included two examples for each of the three major classes of rock, igneous, sedimentary, and metamorphic:


Click here to learn more about the three classes of rocks.



ESCONI Juniors — Spinner and Junior Sales Area
March 4, 2016, 5:30 am
Filed under: ESCONI, Rock Hunters

We used many of the same rock, mineral, and fossil specimens for both the ESCONI spinner and Juniors sales area.

For a quarter a spin (or five spins for a dollar), children could take their chances with the ESCONI spinner. Each spin won at least one mineral, rock, fossil, or shell specimen:


The ESCONI Juniors sales tables included inexpensive rocks, minerals, fossils, and shells that were sold only to children and their teachers. The next photo includes examples of the specimens we had for sale.  If you click on the photo, you can see a much larger version of it, with better looks at the specimens and their labels:


For more photos of the Juniors sales tables, scroll down to the bottom of this page. If you click to enlarge those photos, you may be able to identify specimens that you bought at the ESCONI Juniors booth.

The next few photos identify some of these more common specimens available at the spinner and sales tables. For each type of specimen we give as much information as we have about it. Because some donors did not provide much information about their specimens (or that information was misplaced during storage), we sometimes don’t know where specimens were found or, for fossils, how old they are.


Peeled Sheets of Muscovite Mica

Muscovite is one of several types of the mineral, mica. It is sometimes called white mica. One of the amazing features of this mineral is that thin, flexible, transparent sheets of mica can be peeled off the thicker crystals. The peeled sheets of muscovite shown in the following photo were one of the specimens you could win at the ESCONI spinner:


To learn more about Muscovite Mica, click here or click here.

Quartz Crystals

There were several sizes of quartz crystals available at the spinner and sales tables. Here are examples of the smallest and clearest crystals, which were a couple of centimeters long:


You can find quartz crystals like these in places like Hot Springs, Arkansas. To learn more about the mineral, quartz, click here. To learn more about the quartz crystals found in the Hot Springs, Arkansas, area, click here.

Copper Ore

The greenish and bluish coloring on the rocks in this photo are different minerals that contain the element, copper:


The rocks in the photo came from a copper mine, possibly in Arizona or Nevada. Because the rocks are rich in copper mineral, they can be used as an ore of copper. To learn more about copper ore and copper minerals, click here or click here.



Young collectors could win several types of polished rocks at the ESCONI spinner, or buy them at the sales table. (These polished rocks had all been run through rock tumblers to make them rounded and polished, so they were super smooth. To learn more about tumbling rocks, click here or click here.)

Here are two types of polished rocks that we had available this year.

Polished Beach Pebbles

These included common types of rocks; like granite and limestone, that can be found on Lake Michigan beaches. Here are some examples (mostly varieties of granite):


Polished Agates

Agate is a color-banded variety of quartz. (The crystals in agate are so small that it’s hard to see them even with a microscope.) Some of the agates at the Juniors table were collected on the shores of the Great Lakes (especially Lake Superior), but others came from the western United States, or other countries. Here are some examples:


To learn more about agates, click here. To learn more about Lake  Superior Agates, click here or click here.



If you click on the photos below, you can enlarge them and perhaps identify specimens that you bought at the Juniors booth (or won at the spinner). The first two photos are mostly fossils, and the last photo is mostly rocks and minerals.

After looking at the photos, if you still cannot identify something you obtained at the ESCONI Juniors booth, email me a photo of the specimen, and I’ll see if I can tell you what it is. (I’m Eric Gyllenhaal at )




ESCONI Juniors — Grab Bag Specimens
March 4, 2016, 5:30 am
Filed under: ESCONI, Rock Hunters

One of the free activities at the 2016 ESCONI Juniors booth was the ESCONI Grab Bag. When children arrived at the booth, they were given a brown paper lunch bag. They could select one each of eight different rock, mineral, fossil, and shell specimens to add to their bag. Photos and identification information about the Grab Bag specimens is located further down on this page. First, here are two photos that show what the Grab Bag table looked like in 2014:


The rest of this page consists of close up photos, names, and additional information  about the specimens that were included in ESCONI Grab Bags at the 2015 and 2016 shows. For each type of specimen we give as much information as we have about it. However, because some donors did not provide much information about their specimens (or that information was misplaced during storage), we sometimes don’t know where specimens were found or, for fossils, how old they are.


NOTE:  We will be adding more specimens to this page during the next few days, as we add more specimens to the Grab Bag activity. We will also add more information and links about these specimens as time allows, so be sure to check back here during the week after the ESCONI show.


Specular Hematite, Michigan


Specular Hematite is a type of iron ore made up of tiny, shiny, flattened crystals of hematite. The specimens passed out at Wonder Works came from the iron-mining region of Upper Michigan. Click here to learn more about the mineral hematite.

Selenite Crystals:

Selenite is the crystalline  form of the mineral, gypsum. We are not sure where these crystals were found, although specimens like these can be found in Illinois:


Hourglass Selenite Crystals, Oklahoma

Selenite is a crystal form of the mineral gypsum. These particular selenite crystals are a very special variety from the Salt Plains region of Oklahoma:


The crystals grew inside the salty, sandy soil of this region, trapping sand inside the crystals. Because the sand often forms an hourglass-like shape inside the transparent crystals, this variety is called Hourglass Selenite. Growing crystals sometimes bumped into each other, forming interlocked shapes.  Click here to learn more about Hourglass Selenite.

Amethyst Chips

Amethyst is a purple variety of the mineral quartz:


Quartz Chips:

This chips were broken off of larger crystals of clear or slightly milky quartz:



Chalcedony is a variety of the mineral, quartz, with crystals that are super small — too small to be seen without a powerful microscope. These pieces of chalcedony have been run through a rock tumbler, although only a few of them took a good polish:



The small polished rocks at the Grab Bag table are a mix or mineral, rock, and fossil specimens:



The pieces of broken geode in this photo came from specimens that were found in southwestern Illinois:


The two specimens on the left in this photo show the dull-looking outside of the geodes. The two pieces in the middle show the tiny quartz crystals that line the insides of most of the broken geodes. The geode piece on the lower right shows calcite crystals, which we found in a few geodes. The upper right specimen shows the coating of white clay found in some of our geodes.(This kind of clay is made of crystals so small that they are hard to see even with a microscope.)

Click here to learn more about the geodes found in Illinois.

Click here to learn about one place you can collect geodes in Illinois.



Apache Tears, Western United States

Apache tears are rounded lumps of obsidian, also known as volcanic glass:



Pumice is a type of volcanic rock. It formed from the same type of lava that makes obsidian, but it was very bubbly as it cooled:



The coal in the photo below was broken off of rounded lumps of coal that washed up on a Lake Michigan beach:


The Grab Bag table also gave away small bags containing pieces of Illinois coal (at least while supplies lasted).


Taconite is a processed form of iron ore. It is often transported by train through the Chicago area on its way from the Minnesota iron Ranges to steel mills on southern Lake Michigan, so you can find spilled taconite along local railroad tracks:




Fossil Sea Life from Illinois

The Grab Bag table included specimens of ancient sea animals from several localities. For instance, this sample from Ogelsby, Illinois, dates back to the Pennsylvanian period (about 300 million years ago) It includes mostly brachiopod shells, but two pieces of crinoid stem and two horn corals in the middle of the photo:


The photo below shows more Pennsylvanian age brachiopods, but these are from the Lone Star Quarry in Illinois:


Petrified Wood

The Grab Bag table included specimens of petrified wood from the western United States. If you look closely, you can see the grain of the original wood preserved in rock:


Fossil Shark and Ray Teeth from Africa

These fossil teeth were collected in Morocco. The shark teeth are on the left, and the three ray teeth are on the right:


The sharks and rays lived near the end of dinosaur times, about 60 to 70 million years ago.



The tiny sea shells at the Grab Bag table are a mix of modern day univalves (like snails) and bivalves (like clams). Many of them came from the Indian Ocean: