Indianapolis
Location:
39.826761 N, 86.138582 W
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US/Canada, find the
zip code, and
go here for
specific location info
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worldwide,
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To learn how to turn decimal representation
of latitude/longitude into minutes/seconds
Magnetic Declination
of Indiana for 1999: 3º 7' W
for older
declination,
go here.
for more up-to-the-minute declination,
go here.
Maps
Indiana County Map
Indiana Shaded Relief Map
Satellite Image
Interactive Indiana Maps
(Indiana Geological Survey)
Indiana Data Map (Census
Bureau)
find a USGS quadrangle map
Total Indiana
Population: 5,820,000
Demographics and population
resources
Access
Indiana Geography
Indiana
Geology Today
Not wanting to duplicate a perfectly good resource,
for Indiana geology info, go
here!
Some Indiana Geology
Facts (from
Indiana Geology Today)
Bedrock Geology
The entire
bedrock surface of
Indiana consists of
sedimentary rocks.
The major kinds of sedimentary rock in Indiana
include
limestone,
dolomite,
shale,
sandstone, and
siltstone.
Structure
Indiana is a large
anticline that
plunges to the northwest.
Bedrock Ages
Rocks
age from southeast to the west and north (geologic
time scale,
fun geologic time scale).
The oldest (exposed in the southeast) are Upper
Ordovician
(~440-446 millions of years ago [mya]); this is the
Maquoketa Group
(shale and limestone). The youngest are exposed in
the southwest; they are
Pennsylvanian and
comprise the
McLeansboro Group
(mostly sandstone and shale with discontinuous beds
of coal and limestone).
Indiana Limestone
The most famous Indiana geology is a sequence of carbonate
rocks that is 250 to nearly 500 feet thick and has
significant amounts of gypsum, anhydrite, shale,
chert, and calcareous sandstone. These rocks make up
the
Sanders and
Blue River Groups.
Within the Sanders Group is a formation known by
geologists as the Salem Limestone and by architects
as "Indiana Limestone." This thickly bedded
limestone is
quarried for a
variety of architectural purposes and is known as
one of the premier dimension stones in the world.
Karst
Another Indiana trademark is
karst, the
weathering of limestone by acid dissolution that
produces sink holes, caves, and other features. The
Mitchell Plain, an area of relatively low relief, is
pockmarked by sinkholes and underlain by extensive
cave systems developed in the Mississippian age
limestone bedrock. Surface drainage on the Mitchell
Plain is rare because most streams disappear at
various points along their reach into caves and
joints developed within the rock. Stream erosion and
dissolution of limestone by weakly acidic
precipitation are the principal means of erosion
that produced the Mitchell Plain.
Glaciation
Finally, Central and Northern Indiana geology is the product
of
glaciation. The
early 20th -century geographer C.R. Dryer referred
to the terrain of central Indiana as so monotonous
that a visitor to the region "may ride upon the
railroad train for hours without seeing a greater
elevation than a haystack or a pile of sawdust."
Called the
Tipton Till Plain,
this flat to gently rolling surface is the product
of continental glaciation during the Ice Age.
Sediments borne by the ice sheets were deposited as
till (an unsorted mixture of sand, silt, clay and
boulders) when the glaciers advanced into Indiana
and as outwash sand and gravel when the ice melted.
Thick accumulations of till and outwash filled the
bedrock valleys and covered the bedrock hills of
northern Indiana to produce the flat to gently
rolling landscape thought of by many as monotonous.
IGS Glossary
(from whence most of the above definitions come)
