Mount St. Helens is situated in North America on the North American plate. It is the peak of the fold mountain range in North America. The fold mountain range was formed around 70 million years ago when a convergent plate boundary, Juan De Fuca Plate (Oceanic Crust), collided with the North American Plate (Continental Crust). The oceanic crust was forced downwards into the mantle causing it to turn into magma. Then the pressure increased in the mantle causing the magma to rise up onto the earth's surface. This lead to volcanic eruptions. Many more volcanic eruptions happened at the plate boundary forming Mount St. Helens. Altogether 13 volcano peaks were formed (including Mount St. Helens). This is called the Cascade Range.

Mount St. Helens is the youngest and most deadly of the 13 volcanoes in the Cascade Range. The geologists call Mount St. Helens a composite volcano. It is called this because of its steep sides and its construction. It is made from alternate layers of lava flows, ash, and other volcanic debris. Composite volcanoes mainly erupt explosively causing danger to the nearby wildlife and property.

Many people live around Mount St. Helens. This is beca

The rest of the day the Mount St. Helens deposited ash over the whole area. Deposits were 1cm thick in the town of Yakima. Yakima is 120km away from Mount St. Helens. The air was choked by masses of gas. Volcanic debris from the magma fell onto the remains of the northern slope mountain. These deposits are called bombs or pyroclasts. The swirling ash particles caused lightning to form which started forest fires.

At 8:32am an earthquake (5 on the Richter scale) caused the bulge to start cracking. The pressure in the bulge was so great it caused a massive landslide. The landslide was made out of soil, glacial ice, snow and rock. The landslide traveled 100mph down the side of the volcano into Spirit Lake. The material with the water flung out of the lake and moved down Toutle valley as a mudflow. It eventually blocked the channel of the Columbia River 60km away from the volcano. This was the biggest landslide ever recorded.

On the 27th of March, Mount St. Helens began to let off gas and steam. It showed us that it was its first significant eruption. Magma started bubbling up and a lot of pressure started building up inside the volcano. A bulge started forming on the northern side of the volcano and this kept on increasing 1.5m a day. The public authorities closed the area surrounding the mountain after being told by geologists. Many people who lived around the area were very unhappy about the closi

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Approximate Word count = 948
Approximate Pages = 4 (250 words per page double spaced)