Bear Butte
Bear
Butte is a volcano in South Dakota. It also stretches on to the
Wyoming state line. Bear Butte is a laccolith. The volcano is made of magma
that was never able to explode out of earths surface. The magma stuck
there, it cooled, crystallized, and solidified. After a while the top rocks
were eroded away. Bear Butte rises 1,253 feet from the ground below.
Bear Butte is also knew with the indians. The volcano, is a site sacred to many of the Plains Tribes. This was also a landmark used by George Armstrong Custer. While he was on his trip to the Black Hills in search of gold.
Mount Hood is the tallest mountain in Oregon. It stands 11,237 feet. It is 45 miles east of Portland. Mount Hood is a stratovolcano made of lava flows, domes, and volcaniclastic deposits. The top of Mount Hood formed about 500,000 years ago. The volcano has had 4 eruptive periods in the last 15,000 years. Its last eruptive period was from 180-250 years ago.
The south side of Mount Hood is interesting . The dashed line outlines
the fan of pyroclastic flow deposits and mud flows that formed about 1,500-1,800
years ago. The remnants of a dome that erupted about 200-300 years ago
is in the center of Mount Hood's crater. There are other remants of the
volcanic burst. On the west side there is a remnant of a dome that erupted
about 200-300 years ago, it rises 560 feet above the crater of Mount
Hood.
Volcano
Hazards
The
volcano has many hazards. For one the lava can be very hot, and it travels
at fast speeds. The high heat of the lava burns anything and everything
in its path. Including you so be careful, very careful. The number of
deaths that go along with volcano have increased dramatically within the
last hundred years. Another thing that comes with volcanoes are pyroclastic
surges. Pyroclastic surges are very hazardous. Such surges can bury, burn,
and destroy things as soon as they come into contact with each other.
The
most deadly volcanoes were Nevado del Ruiz, Colombia, Mount Pelée,
Martinique, Krakatau, Indonesia. All of these volcanoes killed over 25,000
people
There are many cause of eruptions. Within the Earth it is so hot that the rock starts to bake as it would in an oven. After a while the liquid rock starts to rise like a cake would. Eventually some of the magma pushes through vents and goes up to the Earth's surface. A volcanic eruption occursCauses of Eruption
Watch
out! A Volcano is Coming!
You will know if a volcano is coming if these things
happen. You will see a rise of magma toward the surface of the volcano.
You will also notice heat flow or changes in the temperature and chemistry
of the ground and spring waters. There will also be noticeable steaming
from the volcano vent. Along with the steaming there is areas of hot ground
that might be enlarged. Gases may also come before eruptions.
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