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 North Carolina volcanic features or events and is by no means inclusive.]
North Carolina can be divided into three physiographic provinces: the Coastal Plain, the Piedmont and the Blue Ridge. Each province is characterized by particular types of landforms.
Within North Carolina, 43 peaks exceed 6,000 feet
in elevation and 82 peaks are between 5,000 and 6,000 feet.
On the west, the Great Smoky
Mountains is the dominant range with several peaks
that reach more than 6,000 feet. On the eastern
side of the North Carolina Blue Ridge, the highest
range is the Black Mountains which
extend for some 15 miles and contain
a dozen peaks that exceed 6,000 feet in elevation.
This group includes Mount
Mitchell. At an elevation of 6,684 feet
in elevation, it is the highest peak of
eastern North America. Other prominent
ranges from northeast to
southwest are the Pisgah Mountains,
Newfound Mountains, Balsam Mountains,
Nantahala Mountains, and the Valley River Mountains.
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The Appalachians:2
The Atlantic Plain:2 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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Ocoee Basin:3
Volcanoes:3
Development of the Appalachains:3
More Volcanoes:3
Metamorphic Rocks:3
Atlantic Ocean Forms:3
Creating the Appalachians of Today:3
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| North Carolina's Geologic Belts |
North Carolina Rocks and Geologic Belts:1
Three major classes of rocks common to
North Carolina are igneous, metamorphic and sedimentary.
North Carolina has a long and complex history.
Although much remains to be learned, detailed
geologic studies provide a general understanding
of regional geological relationships. The State is best
described in terms of geological belts;
that is, areas with similar rock types and geologic history.
From West to East:1
| North Carolina's Volcanic Rocks |
North Carolina's Granite:1
The General Assembly of 1979 designated
granite as the official State rock.
North Carolina is blessed with an abundance
of granite.
When granite is crushed, it is used
as an aggregate for road and building construction.
If granite has the right
physical properties, it can be cut into blocks
and used for monuments, curb stone and stone
for building facings. The largest open face granite
quarry in the world is
located at Mount Airy, North Carolina.
North Carolina's Olivine:1
Olivine occurs as isolated dunite bodies,
or alpine-type peridotites, in the Blue Ridge.
Two main districts, the
Webster-Balsam district in Jackson County
and the Spruce Pine district in Yancey and
Mitchell counties, have produced
most of the olivine. The deposits contain
50 to 90 percent olivine.
North Carolina leads
the nation in olivine production, although
production is presently limited to the
Daybrook Mine near Burnsville in Yancey County.
North Carolina's Pegmatites:3
Some molten granitic rock cools very slowly
and forms coarse-grained veins called
pegmatites.
These have been the source of
high-purity minerals, such as feldspar,
quartz, and mica, and gemstones, such as
emerald and beryl.
The main uses of feldspar are in glass, pottery,
and ceramics.
| North Carolina's Garnet Deposits |
North Carolina's Garnet Deposits:4
Large deposits of almandite and rhodolite
garnet of gem and abrasive quality are
known in Clay, Jackson, Macon, Madison, and
Burke Counties. Abrasive-grade garnet was
produced from some of these deposits from
1900 to about 1926, but no production has been recorded
recently. The deposit of almandite garnet
in Clay County is in a hornblende gneiss at
Penland Bald on Buck Creek.
Fine red colored, gem-quality pyrope
garnets have been found in the wastes
from placer gold operations in
Burke, McDowell, and Alexander
Counties. Rose-pink rhodolite garnets
are recovered from gravels in Cowee Creek
near Franklin, and Mason's Branch near Iotla, both in Macon
County. Rhodolite can be found in situ on Mason Mountain.
| North Carolina's Metallic Minerals |
North Carolina's Metallic Minerals:1
Metallic minerals are associated principally
with the igneous and metamorphic rocks of the
Piedmont and Blue Ridge
geologic belts.
Ores of chromium, copper,
gold and silver, iron, lead and zinc, manganese,
molybdenum, nickel, tin,
titanium, and tungsten all occur in either the
Piedmont or Mountain Provinces.
| Appalachian Mountains |
| Black Mountains |
Black Mountains:5
More than a billion years ago, the Black Mountains were
formed. This mighty range of peaks once stood lofty and
rugged. But over millions of years, wind, water and other
forces wore down the pinnacles to their rounded, more
subdued profile of today.
Only the erosion-resistant
igneous and metamorphic rocks allowed Mount Mitchell
to retain its dramatic height of 6,684 feet.
Because of the even elevation of its ridgeline, the Black
Mountain range was referred to as a single mountain
until the late 1850s. Of the separate peaks that have
since been designated, six are among the ten highest in
the eastern United States. Although the Black Mountain
range is higher, its length and breadth do not equal that
of the nearby Blue Ridge or Great Smoky mountains.
From the air, the range bears the shape of the letter J,
and the distance between its end points -- Yeates Knob
and Celo Knob -- is merely 15 miles.
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Blue Ridge National Parkway
North Carolina and Virginia |
North Carolina's Blue Ridge:1
The Blue Ridge is a deeply
dissected mountainous area of
numerous steep mountain ridges,
intermontane basins and trench
valleys that intersect at all
angles and give the area its
rugged mountain character.
The Blue Ridge contains the highest
elevations and the most rugged topography in the
Appalachian Mountain system of
eastern North America. The North Carolina
portion of the Blue Ridge is about
200 miles long and ranges from 15 to
55 miles wide. It contains an area of
about 6,000 square miles, or about 10
percent of the area of the state.
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Great Smoky Mountains National Park
North Carolina and Tennessee |
| Looking Glass Rock |
Looking Glass Rock:3
As blocks of continental crust rode across
one another, some rocks became so hot that
they melted. Molten rock at the Earth's
surface erupts to form either volcanoes
or quiet lava flows.
When molten
remains deep below ground, it cools
crystallizes to form bodies of rock that
called igneous plutons.
Plutons are scattered throughout the
Southern Appalachians like plums in a
pudding.
Some plutons are now exposed at the
land surface due to erosion of overlying
rock; they weather to form unusual,
smooth-sided domes like Looking Glass Rock,
south of Asheville, North Carolina.
The plutons are composed of granite and
similar rocks.
| Medoc Mountain State Park |
Medoc Mountain:5
Medoc Mountain is not really a mountain at all; its
highest point reaches an elevation of only 325 feet
above sea level. It is, rather, the core of what was once a
mighty range of mountains. Medoc Mountain is what
remains after millions of years of erosion.
The eroded peaks were formed by volcanic action during the
Paleozoic Age, about 350 million years ago.
An elongated structure of biotite granite, Medoc
Mountain has effectively routed the streams of the area
around itself and has resisted the erosion typical of the
surrounding lowlands. The park sits near the fall line, an
area where the hard, resistant rocks of the foothills give
way to the softer rocks and sediments of the coastal
plain. The northern and western faces of Medoc
Mountain have very steep slopes, dropping 160 feet
over a distance of less than a quarter mile. Such rugged
terrain is unusual for the eastern piedmont.
| Mount Airy |
North Carolina's State Rock:1
The General Assembly of 1979 designated
granite as the official State rock.
North Carolina is blessed with an abundance
of granite. When granite is crushed, it is used
as an aggregate for road and building construction.
If granite has the right
physical properties, it can be cut into blocks
and used for monuments, curb stone and stone
for building facings.
The largest open face granite
quarry in the world is
located at Mount Airy, North Carolina.
Dimension Stone:1
Most dimension stone in North Carolina is
produced from granite, agrillite, quartzite, marble, and
sandstone. The North Carolina Granite Company
operates one of the largest granite dimension stone quarries in the world
at Mount Airy in Surry County.
The Mount Airy
granite is a light-colored biotite granitoid
(monzogranite).
The rock is used as
street curbing, ashlar for masonry walls,
rubble, rip-rap, monuments, and sawed blocks for buildings.
| Mount Mitchell State Park |
Mount Mitchell:1
The highest point in North Carolina
(and the highest point east of the Mississippi River)
is Mount Mitchell. Its elevation is 6,684 feet.
Black Mountains and Mount Mitchell:5
More than a billion years ago, the Black Mountains were
formed. This mighty range of peaks once stood lofty and
rugged. But over millions of years, wind, water and other
forces wore down the pinnacles to their rounded, more
subdued profile of today.
Only the erosion-resistant
igneous and metamorphic rocks allowed Mount Mitchell
to retain its dramatic height of 6,684 feet.
Because of the even elevation of its ridgeline, the Black
Mountain range was referred to as a single mountain
until the late 1850s. Of the separate peaks that have
since been designated, six are among the ten highest in
the eastern United States. Although the Black Mountain
range is higher, its length and breadth do not equal that
of the nearby Blue Ridge or Great Smoky mountains.
From the air, the range bears the shape of the letter J,
and the distance between its end points -- Yeates Knob
and Celo Knob -- is merely 15 miles.
| Salisbury Area Granites |
Salisbury Area Granites:1
The colors of
the granite of the Salisbury,
North Carolina area
range from white to pink. These
rocks are sold under a variety of trade names.
The white granite of the Salisbury area
has been used to face a number
of buildings.
| Stone Mountain State Park |
Stone Mountain State Park:5
Stone Mountain is not immediately visible upon entering
the park that bears its name, but
this magnificent
600-foot granite dome
is well worth the wait. Sunlight and
shadows dance across a broad tapestry of stone.
White-tailed deer emerge from the security of the forest
to graze on meadow grasses at the mountain's base.
The scenery is only one attraction of the park.
Test your fly-fishing techniques in more than 17 miles of
designated trout waters. Or, with more than 16 miles of
trails, take a hike in the park. Designated as a National
Natural Landmark in 1975, Stone Mountain is bounded
on the north by the Blue Ridge Parkway and on the west
by the Thurmond Chatham Game Lands. More than
13,747 acres of mountain beauty offer opportunities for
outdoor activities of all kinds.
Stone Mountain:5
One of the park's most spectacular features is
Stone Mountain, a 600-foot granite dome.
This magnificent
feature is part of a 25-square-mile pluton, an igneous
rock formed beneath the earth's surface by molten lava.
Over time, wind, water and other forces gradually eroded
the softer layers of rock atop the granite block and
exposed the outcrop we see today. Wet weather springs
continually carve troughs in the granite as water runs
down the mountain's sloping face.
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