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:
[This list is just a sample of
various Missouri volcanic features or events and is by no means inclusive.]
Excerpt from: |
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The Interior Plains:4
Ouachita-Ozark Interior Highlands:4 The ancient, eroded mountains of the Ouachita-Ozark Highlands stand surrounded by the nearly flat-lying sedimentary rocks and deposits of the Interior and Atlantic Plains provinces. Unlike the relatively young rocks that characterize neighboring provinces, the rocky outcrops that make up the core of the Ouachita-Ozark Highlands are Paleozoic age carbonate and other sedimentary rocks that were originally deposited on the sea floor. In the Ouachita Mountains these ancient marine rocks are now contorted by folds and faults. These rocks closely match deformed strata found today in the Marathon Mountains of Texas and the southern Appalachians -- strong evidence that the Ouachita-Ozark Highlands were once part of a mighty folded, uplifted mountain range that stretched from the Appalachians Highlands to the northeast through Texas to the southwest.
The Atlantic Plain:4 The Atlantic Plain is the flattest of the provinces. It stretches over 2,200 miles in length from Cape Cod to the Mexican border and southward another 1000 miles to the Yucatan Peninsula. The Atlantic plain slopes gently seaward from the inland highlands in a series of terraces. This gentle slope continues far into the Atlantic and Gulf of Mexico, forming the continental shelf. This region was born during the breakup of the supercontinent Pangea in the early Mesozoic Era.
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| Missouri Red Granite |
Missouri Red Granite:2
This red granite,
first commercially quarried in the late 1800s,
has been used as building material and as paving blocks
for the St. Louis levee and downtown streets.
Today, "Missouri Red" granite is cut and polished
mainly for use as monuments.
The Streets of St. Louis and the Governor's Mansion:3
The oldest granite
quarry in the
state opened near Graniteville in 1869. The granite takes a high polish and is ideal for
tombstones and building stone. Granite taken from the site furnished stone for the Eads Bridge
and the cobblestone streets of St. Louis. Other quarries north of Elephant Rocks (see below) supplied the
turned columns in the front porch of the Governor's Mansion in Jefferson City.
| Elephant Rocks State Park |
Elephant Rocks State Park:2
Imagine giant granite rocks
standing end-to-end like a train
of circus elephants. That's what you'll see at Elephant
Rocks State Park.
About 1.5 billion years ago, hot magma
cooled forming coarsely crystalline red granite, which later
weathered into huge, rounded boulders.
Standing atop a
granite outcrop, one of the largest elephant rocks, Dumbo,
tops the scales at a whopping 680 tons!
Visitors to Elephant Rocks State Park can easily view the
granite boulders from the one-mile Braille Trail, designed to
accommodate people with visual or physical disabilities.
The trail passes by a quarry pond, which now supports a
variety of animal life. A short spur off of the trail takes
visitors to the top of the granite outcrop, where they can
explore the maze of giant elephant rocks.
A second spur brings visitors to a point overlooking
an old quarry site. This red granite, first
commercially quarried in the late 1800s, has been used
as building material and as paving blocks
for the St. Louis levee and downtown streets. Today,
"Missouri Red" granite is cut and polished
mainly for use as monuments. Thirty picnic sites allow
visitors to rest and have a cool drink
among the stone pachyderms. Come see for yourself why
Elephant Rocks State Park is a place
you'll never forget!
More Elephant Rocks State Park:3
These ancient
pachyderms aren't performing in a circus or
languishing in a zoo because they are huge
elephant-shaped igneous rocks crowning the
high point of Elephant Rocks State Park.
The herd
of pink granite "elephants" weigh about
160 pounds per cubic foot and stand 20 to 30 feet tall.
"Dumbo", the matriarch of the troop, weighs
about 680 tons, stands 27 feet tall, and measures
35 feet long and 17 feet wide. She and her family of spherical,
egglike masses of eroded pink
granite were created by the same forces that
produced the Ozark Mountains.
| Ozark Mountains |
Ozark Mountains:3
Most of Missouri south of the Missouri River,
and parts of northern Arkansas, northeastern
Oklahoma, and southern Illinois are known nationwide as the Ozarks.
The region covers about
50,000 square miles, with 33,000 square miles
being in Missouri, 13,000 in Arkansas, 3,000 in
Oklahoma, and 1,000 in Illinois. This rugged area is
characterized by lofty hills, deep
valleys, cold clear springs and streams, large caves, and a unique cultural tradition.
Although its borders blend into the surrounding countryside, the Ozarks are roughly bordered by
the Missouri River on the north, and Mississippi River on the east, the Arkansas River on the
south, and the Arkansas, Neosho, and Osage rivers on the west.
The presently accepted theory of origin for the Ozarks is that during the millions of years
when parts of the state were being submerged, uplifted, and re-submerged in warm, shallow seas,
the Ozark region was being slowly and continuously uplifted. As the massive land area pushed
upward, the rugged topography was sculpted by erosion. What we see today is a landscape
changed by the weather of million of years, including last winter's blizzard and today's
rainstorm.
St. Francois Mountains:3
The "top" of the Missouri Ozarks is in the St. Francois Mountains,
an area composed of the
oldest rocks in the state.
The highest elevation is 1,772-foot Taum Sauk Mountain.
These
peaks were formed by the erosion of igneous rocks
which originated as volcanic eruptions and
molten intrusions approximately 1.3 to 1.5 billion years ago.
Taum Sauk Mountain State Park and the Devil's Toll Gate:2
The state's highest point - 1,772 feet above sea level -
is the centerpiece of this rugged
6,888-acre state park located in the scenic St. Francois Mountains.
The park also contains
Mina Sauk Falls, the state's highest waterfall,
and a geological wonder known as the Devil's Toll Gate.
The wooded igneous rock
knobs are dotted with glades covered in thick mantels of
prairie grass.
Rugged hiking trails, including a portion of the
Ozark Trail, picnicking facilities, and
a primitive camping area are available.
Volcanic Outcrops:3
The red and gray igneous rock outcrops (mostly
granite and rhyolite)
of the Ozarks
are
comparable to knobby rock islands in a weathered sea of sediments.
These sediments consist of
layered units of dolomite, limestone, sandstone, shale, and chert.
| Volcanic Ash Deposits |
Ash Deposits from Yellowstone Caldera:1
Ash deposits
from these powerful eruptions have been mapped as far away as
Iowa, Missouri, Texas, and even
northern Mexico.
Excerpts from:
1) Kious and Tilling, 1996,
This Dynamic Earth: The Story of Plate Tectonics:
USGS Special Interest Publication
2) Missouri State Parks and Historic Sites Website, 2001
3) Missouri Department of Natural Resources Website, 2001
4)
USGS/NPS Geology in the Parks Website, 2001
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