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America's Volcanic Past

"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

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Map, Location of Missouri

Volcanic Highlights and Features:
[NOTE: This list is just a sample of various Missouri 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 Missouri.]

  • Missouri
  • Missouri Regions
  • Missouri Red Granite
  • Elephant Rocks State Park
  • Ozark Mountains
  • Volcanic Ash Deposits


Excerpt from:

The Interior Plains:4
The Interior Plains is a vast region that spreads across the stable core (craton) of North America. This area had formed when several small continents collided and welded together well over a billion years ago, during the Precambrian. Precambrian metamorphic and igneous rocks now form the basement of the Interior Plains and make up the stable nucleus of North America. With the exception of the Black Hills of South Dakota, the entire region has low relief, reflecting more than 500 million years of relative tectonic stability.

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.


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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01/28/03, Lyn Topinka