dumb...
...as a box of rocks.
Iron-stone concretions to be cracked open looking for fossils. There is an area south of Chicago where the land was strip-mined for coal. The overburden of soil contains fossils from the Pennsylvanian era. These fossils were composed of plants and animals living in a very shallow sea and swamps. These organisms died and were buried in an iron rich mud. Over millions of years, they fossilized inside these brown iron rich concretions. Fish, insects, plants of all kinds, leaves, amphibians, arthropods and Illinois only State fossil, the Tully Monster. This lagerstatten is called Mazon Creek. A lagerstatten is a place where there is a concentration of fossils of great variety and of one geologic era. These concretions come in many sizes and are usually flattened ovals to round stones of this brownish color. They are strewn in the overburden and weather out or are dug out of the ground. One needs to crack them open by repeatedly freezing and thawing them or by using a rock hammer to open them. Maybe one in 30 yield a recognizable fossil.
dumb...
...as a box of rocks.
Iron-stone concretions to be cracked open looking for fossils. There is an area south of Chicago where the land was strip-mined for coal. The overburden of soil contains fossils from the Pennsylvanian era. These fossils were composed of plants and animals living in a very shallow sea and swamps. These organisms died and were buried in an iron rich mud. Over millions of years, they fossilized inside these brown iron rich concretions. Fish, insects, plants of all kinds, leaves, amphibians, arthropods and Illinois only State fossil, the Tully Monster. This lagerstatten is called Mazon Creek. A lagerstatten is a place where there is a concentration of fossils of great variety and of one geologic era. These concretions come in many sizes and are usually flattened ovals to round stones of this brownish color. They are strewn in the overburden and weather out or are dug out of the ground. One needs to crack them open by repeatedly freezing and thawing them or by using a rock hammer to open them. Maybe one in 30 yield a recognizable fossil.