butte

isolated hill with steep sides and a flat top

st. peters sandstone

soft rock made of a hard material i.e. compressed grains of silica, st. peters is pure quartz

what is sandstone used for?

st. peters sandstone is used in glass production either commercially or in construction

advancing

when a glacier moves faster than it melts

retreating

when a glacier is melting faster than it is moving

stagnant

when a glacier is melting at about the same rate it is moving & the forward motion has stopped

drift

dropped rock material, called till when at the point of melting

moraine

a mass of drift carried down and deposited by a glacier, formed to a pile through glacial stagnancy

Ordovician period

period that our sedimentary rocks were formed

main glaciations

Illinois & Wisconsin

Pleistocene period

period when glaciers advanced & retreated over the last 1.8 million years

how was st peter sandstone formed

the ancient seabed was compressed over time to form sand. weaker minerals eroded & left behind the purest element: quartz

how were canyons formed

canyons were formed 16,000 years ago from a drastic flood called the Kankakee Torrent as the meltwater streams from glaciers were released.

anticline

a group of rock strata bent upward due to a folding, ex. the Lasalle anticline

tribes present in Illinois Alliance

Kaskaskia, Peoria, Cahokia, Tamaroa, and Michigamea

legend of Starved Rock

Illinois tribe was trapped at the top, surrounded by the Odawa (Ottawa) and Potawatomi, and starved to death at the top of the rock.