||Trevor Major, M.Sc., M.A.
Have there ever been times when your mother let soup boil over on the stove? Parts of the Earth also are boiling over. Far below the Earth’s surface, rock is melting under tremendous heat. As it melts, the rock expands, becomes less dense, and rises toward the crust. Sometimes, the crust acts like a lid on a saucepan, stopping this hot liquid rock or magma (MAG-muh) from coming to the surface. There it could cool, without anyone ever knowing. At other times, the magma will find a crack or weakness in the crust. When it reaches the surface, scientists call it lava (LAH-vuh). A volcano (vol-CAY-no) forms wherever lava builds up on the surface of the Earth.
Different types of lava form different types of volcanoes. Hot, runny lavas often cause relatively gentle eruptions. Cooler, pasty lavas often cause violent eruptions. This is because gases can escape from a runny lava better than they can from a pasty lava. The less gas, the less pressure there is on the rising magma.
The lavas of Hawaii’s Mauna Loa are hot and runny. They pour out of the opening or crater (CRAY-ter) and flow many miles. With an explosive volcano, like Mount St. Helens, lava, rocks, steam, and water can shoot out at great speed. The explosion reduces rock and lava to a fine powder called ash. Wind can spread this volcanic ash all over the world.
Genesis 8:4 says that the ark of Noah came to rest on the mountains of Ararat (AR-uh-rat). Mount Ararat itself is one of the most active volcanoes in the world. The Bible mentions another volcanic area called Bashan (buh-SHUHN). The place is rocky, but good rainfall, plus rich soil formed from the lava, has made it a prosperous farming region (Deuteronomy 32:14; Psalm 22:12; Ezekiel 39:18).