Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Geol G-308
Paleontology and Geology of Indiana
Overview of Indiana
Bedrock Geology
P. David Polly
Department of Geological Sciences
Indiana University
Bloomington, Indiana 47405 USA
[email protected]
Indiana bedrock geology
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Objectives
1. Indiana’s bedrock geological map
2. Cross-section of bedrock geology in Indiana
3. Large and small scale geological maps
4. William Smith and the first geological map
5. Stratigraphic column of Indiana
6. Stratigraphic terminology
7. David Dale Owen and geology of the Mississippi Basin
8. Overview of events represented in Indiana’s rocks
Geol G-308
Paleontology and Geology of Indiana
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Geol G-308
Paleontology and Geology of Indiana
About geological maps
•
Regions are color-coded by the age of the
rocks
•
Small scale maps (i.e., ones that cover large
areas) are simplified by combining rock units
into larger and larger age categories
•
Bedrock geology consists of rock units that
are lithified and extend below the surface (in
most cases)
•
Bedrock geology is distinguished from
surficial geology, which consists of rock, dust,
mud, sand, soils, and other lithic debris that
has been left on the surface of the bedrock
by rivers, streams, wind, glaciers, etc.
Map of Indiana Showing Bedrock Geology. 1990.
Drafted by Kimberly Sowder. Indiana Geological Survey.
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Geol G-308
Paleontology and Geology of Indiana
Bedrock geological map
Map of Indiana Showing Bedrock Geology. 1990.
Drafted by Kimberly Sowder. Indiana Geological Survey.
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Geol G-308
Paleontology and Geology of Indiana
Cross section (west to east) of
Indiana’s major rock units
Map of Indiana Showing Bedrock Geology. 1990.
Drafted by Kimberly Sowder. Indiana Geological Survey.
Department of Geological Sciences | Indiana University
Geol G-308
Paleontology and Geology of Indiana
(c) 2012, P. David Polly
Bedrock geology of Monroe County
Edwardsville Fm.
(Borden River Delta)
Salem Limestone and others
(Shallow tropical seas)
Limestones
Sandstones, Shales,
and Coals
(Nearshore seas and
Terrestrial Swamps)
Youngest (320 mya)
Pennsylvanian
Oldest (360 mya)
Earlier Mississippian
Bedrock Geology of Indiana. 2002.
H. H. Gray (data compiler). Indiana Geological Survey.
Department of Geological Sciences | Indiana University
Geol G-308
Paleontology and Geology of Indiana
(c) 2012, P. David Polly
William Smith and the first geological map
Wm. Smith
(1769-1839)
British canals
Canal lock in Essex, England
William Smith
monument in
Churchill, England
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Geol G-308
Paleontology and Geology of Indiana
William Smith’s Observations
•
Different types of rock were not
distributed randomly
•
Different types of rock could be
mapped as units
•
If a rock unit lay on top of another in
one area, it did in other areas as well
•
Sedimentary rock units each had
unique fossils that were not found in
other units
William Smith’s 1815 Geological Map
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
19th Century canals in North America
Geol G-308
Paleontology and Geology of Indiana
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Geol G-308
Paleontology and Geology of Indiana
Stratigraphic
columns are the
“keys” to
geological maps
Indiana Geological Survey
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Geol G-308
Paleontology and Geology of Indiana
Terminology
Chronostratigraphic units – units of time. Periods in the basic geological timescale are
chronostratigraphic units, as are units measured in millions of years ago. From large to small
these units are called eons, eras, periods, epochs, and ages. For example, “the first land
plants evolved during the Silurian Period”. This sentence makes no reference to any particular
rocks, only to a time in the Earth’s past.
Time-stratigraphic units – units of rock that belong to a certain time period. Groupings of
rock layers based on their geological age are time-stratigraphic units. From larger to smaller
these units are called systems, series, and stages. Temporal groups of rocks usually have a
corresponding time unit with the same name. For example, “The Silurian System in Indiana
was formed during the Siluran Era”.
Lithological units – mappable units of rocks that have similar age and the same general
lithology. Groupings of rock layers as you see them in the ground. Usually rocks that are
grouped together this way formed in the same environment (such as the delta of a particular
ancient river). Formations are the basic lithological unit. Formations are divided into
members and beds, and grouped into groups. Example, “The Borden Group contains the
Edwardsville Formation and is Mississippian in age”.
Department of Geological Sciences | Indiana University
(c) 2012, P. David Polly
Geol G-308
Paleontology and Geology of Indiana
Stratigraphy in Indiana
David Dale Owen (1807-1860)
•
Stratigrapher and geologist, Dale
Owen was a son of Robert Owen, the
socialist utopian who founded New
Harmony, Indiana.
•
Dale Owen conducted the first
geological survey of Indiana, Kentucky,
Arkansas, Iowa, Minnesota and
Wisconsin
•
In 1860, Owen’s museum in New
Harmony was the largest west
of the Appalachians.
New Harmony
Ground sloth skeleton from
Owen’s Museum, shown here
in it’s later home at Indiana
University
Department of Geological Sciences | Indiana University
Geol G-308
Paleontology and Geology of Indiana
(c) 2012, P. David Polly
Bedrock Geology Overview
Coal swamps
Ordovician
First land animals
Oldest
(470 mya)
Silurian
Devonian
First land
plants
Mississippian
Pennsylvanian
Early fishes
Youngest (300 mya)
Bedrock Geology of Indiana. 2002.
H. H. Gray (data compiler). Indiana Geological Survey.
Department of Geological Sciences | Indiana University
Geol G-308
Paleontology and Geology of Indiana
(c) 2012, P. David Polly
Quaternary geology
The Quaternary
Late mammals
Glacial Till
Early mammals
Late dinosaurs
Early dinosaurs
Mammal-like
Reptiles
Surficial and Bedrock Geology of Indiana. 2002.
H. H. Gray (data compiler). Indiana Geological Survey.