America's Volcanic Past
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"Though few people in the United States may actually experience an erupting volcano, the evidence for earlier volcanism is preserved in many rocks of North America. Features seen in volcanic rocks only hours old are also present in ancient volcanic rocks, both at the surface and buried beneath younger deposits." -- Excerpt from: Brantley, 1994 |
Volcanic Highlights and Features:
[NOTE: This list is just a sample of various Kansas features or events and is by no means inclusive. All information presented here was gathered from other online websites and each excerpt is attributed back to the original source. Please use those sources in referencing any information on this webpage, and please visit those websites for more information on the Geology of Kansas.] |
The Earth is billions of years old. In Kansas, hills were formed that were later buried or worn away by wind and water. Seas covered parts of the state, then disappeared. Giant sheets of ice called glaciers moved into northeast Kansas, then melted. Rivers changed their courses. The climate changed -- sometimes hot, sometimes cold, sometimes wet, sometimes dry. These changes are what made Kansas look the way it does today. Igneous rocks are formed when a hot liquid, called magma, cools and changes from a liquid state to a solid state. They may form slowly underground or rapidly at the Earth's surface. When magma reaches the surface, it is called lava. Lava flows out of a volcano and quickly hardens after an eruption. Although most lava reaches the surface through volcanoes, it may also flow out of deep cracks in the earth without building a mountain. Kansas doesn't have an active volcano, but lava did flow onto the surface as recently as 90 million years ago when dinosaurs still roamed the Earth. Hot magma forced its way up from over 100 miles below the Earth's surface in two small areas of eastern Kansas. The hot liquid, which spread upward through cracks in other underground rocks, cooled and hardened, forming a rock called lamproite in Woodson and Wilson counties and one called kimberlite in Riley County. In one area of Riley County, lava flowed onto the surface but a volcanic cone was never formed. The kimberlite formed from the lava is now buried. Lamproite and kimberlite found at the surface in Kansas were exposed when the rock above was eroded away. Diamonds have been found in kimberlites and lamproites in other parts of the world, but none has been found yet in Kansas. Granite, another type of igneous rock, has been found mixed with lamproite in Woodson County. It is older than the surrounding surface rocks and was formed deep in the Earth. Lamproite magma carried it toward the surface, where it is now exposed.
Some igneous and metamorphic rocks have traveled
into Kansas from other places. Volcanic ash,
basalt, granite, and quartzite have been carried
in by wind, glaciers, and water.
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The Interior Plains:2
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Precambrian:1
Midcontinent Rift:3
Next 500 plus million years:1
Quaternary (last 1.6 million years):1
Cretaceous Igneous Rocks:
Kansas's Interior Plains Region:1
Kansas's Ozark Plateau:1
Kansas's Cherokee Lowlands, Osage Cuestas, and Chautauqua
Hills:1
Kansas's Flint Hills and Red Hills:1
Kansas's Smoky Hills:1
Kansas's High Plains:
Kansas's Arkansas River Lowlands and Wellington-McPherson
Lowlands:1
Kansas's Glaciated Region:1
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Kansas's Rocks and Volcanic Activity |
Kansas's Bentonite:1
Bentonite is a type of clay formed from altered volcanic ash.
Most types of bentonite swell when they absorb water.
Deposits of bentonite
have been found in several locations in western Kansas.
Kansas's Granite:1
Granite, another type of igneous rock,
has been found mixed
with lamproite in Woodson County.
It is older than the surrounding surface
rocks and was formed deep in the Earth. Lamproite magma carried it
toward the surface, where it is now exposed.
Kansas's Kimberlites:1
Unlike most of the surface rocks in Kansas,
which are sedimentary in origin,
kimberlite is an igneous rock,
formed from the cooling of molten
magma.
Igneous rocks are extremely rare in Kansas.
Kimberlite is composed of at least 35% olivine,
together with other minerals such as mica,
serpentine, and calcite.
Geologists call it an ultrabasic rock,
which means it does not contain any quartz
or feldspar, the two
most common rock-forming minerals.
Olivine, the main mineral constituent of the rock,
is an olive-green, grayish green,
or brown mineral made
up of magnesium, iron, and silica.
In 1888, the name kimberlite was proposed
for this particular rock,
based upon the occurrence of these rocks
in the vicinity of Kimberley, South Africa.
Diamonds occur in only two rock types on earth, kimberlites and lamproites, both rare in Kansas. Kimberlite is unique because it originates over 100 miles (150 kilometers) deep in the earth and travels in a matter of hours to the earth's surface where it forms small volcanic features. In Kansas, kimberlites or kimberlite pipes (so-called because of their pipelike, three-dimensional shape) occur in a restricted, northeast-trending belt in Riley and Marshall counties. These rocks were first discovered in Kansas in the late nineteenth century. Since then, more kimberlites have been found -- the last three in the fall of 1999. Thirteen kimberlites have been identified so far, twelve in Riley County and one in Marshall County. Six kimberlites are exposed at the surface; the others are buried under soil up to 25 feet (7.5 meters) thick. Diamonds have been found in kimberlites and lamproites in other parts of the world, but none has been found yet in Kansas.
Kansas kimberlites are located near Tuttle Creek Lake in Riley and Marshall counties. Recently, the Kansas Geological Survey used aeromagnetic survey data to delineate other potential kimberlites. Detailed magnetic surveys on the ground were then conducted at locations derived from the aerial surveys, and drilling in the fall of 1999 confirmed the presence of three additional kimberlites. These are the Tuttle, Baldwin Creek, and Antioch kimberlites. The Tuttle kimberlite is covered by only a few feet of soil, the Baldwin Creek by 25 feet (7.5 meters), and the Antioch by 21 feet (6.4 meters). Each of the three kimberlites was cored to a depth of 300 feet (91 meters) for further studies.
Kansas's Lava Flows:1
Kansas doesn't have an active volcano,
but lava did flow onto the surface as recently
as 90 million years ago when dinosaurs still roamed the
Earth.
Hot magma forced its way up from over 100 miles below
the Earth's surface in two small areas of eastern Kansas. The hot liquid,
which spread upward through cracks in other underground rocks,
cooled and hardened, forming a rock called lamproite in Woodson and
Wilson counties and one called kimberlite in Riley County.
In one area of Riley County, lava flowed onto the surface but a
volcanic cone was never formed. The kimberlite formed from the lava is now
buried. Lamproite and kimberlite found at the surface in
Kansas were exposed when the rock above was eroded away.
Diamonds have been
found in kimberlites and lamproites in other parts of the world,
but none has been found yet in Kansas.
Kansas's Volcanic Ash Deposits:1
Unstable conditions inside the Earth also cause changes.
Volcanic eruptions, such as Mount St. Helens
in Washington in 1980, can cause
immediate changes. When Mount St. Helens erupted, the top of the
mountain blew off and volcanic ash was carried thousands of miles by the
wind.
Millions of years ago, active volcanoes in
New Mexico, Wyoming, and California erupted and
large quantities of ash were carried into
Kansas. Today, volcanic-ash deposits can be found in western Kansas.
Volcanic Rocks from Elsewhere:1
Some igneous and metamorphic rocks
have traveled into Kansas from other places.
Volcanic ash, basalt, granite,
and quartzite have been
carried in by wind, glaciers, and water.
Eastern Kansas |
Lava Flows:1
Kansas doesn't have an active volcano,
but lava did flow onto the surface as recently
as 90 million years ago when dinosaurs still roamed the
Earth. Hot magma forced its way up from over 100 miles below
the Earth's surface in two small areas of eastern Kansas.
The hot liquid,
which spread upward through cracks in other underground rocks,
cooled and hardened, forming a rock called lamproite in Woodson and
Wilson counties and one called kimberlite in Riley County.
In one area of Riley County, lava flowed onto the surface but a
volcanic cone was never formed. The kimberlite formed from the lava is now
buried. Lamproite and kimberlite found at the surface in
Kansas were exposed when the rock above was eroded away. Diamonds have been
found in kimberlites and lamproites in other parts of the world,
but none has been found yet in Kansas.
Western Kansas |
Bentonite:1
Bentonite is a type of clay formed from altered volcanic ash.
Most types of bentonite swell when they absorb water. Deposits of bentonite
have been found in several locations in western Kansas.
Volcanic Ash Deposits:1
Unstable conditions inside the Earth also cause changes.
Volcanic eruptions, such as Mount St. Helens in Washington in 1980, can cause
immediate changes. When Mount St. Helens erupted, the top of the
mountain blew off and volcanic ash was carried thousands of miles by the
wind. Millions of years ago, active volcanoes in
New Mexico, Wyoming, and California erupted and large quantities of ash were carried into
Kansas. Today, volcanic-ash deposits can be found in western Kansas.
Volcanic Ash Deposits |
Volcanic Ash:1
Unstable conditions inside the Earth also cause changes.
Volcanic eruptions, such as Mount St. Helens in Washington in 1980, can cause
immediate changes. When Mount St. Helens erupted, the top of the
mountain blew off and volcanic ash was carried thousands of miles by the
wind. Millions of years ago, active volcanoes in
New Mexico, Wyoming, and California erupted and large quantities of ash were carried into
Kansas. Today, volcanic-ash deposits can be found in western Kansas.
Excerpts from:
1) Kansas Geological Survey Website, 2001
2) USGS/NPS Geology in the Parks Website, 2001
3) Morey, G.B., 2001, Compositions of Rift-Related Volcanic Rocks of the
Keweenawan Supergroup Atop the St. Croix Horst, Southeastern Minnesota:
Minnesota Geological Survey Information Circular 47, 27p.
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