Lava is a molten rock that is expelled from a volcano during an eruption. When lava cools and solidifies, it forms igneous rock. Lava is extremely hot, reaching temperatures of 1,000 to 1,200 degrees Celsius (1,800 to 2,200 degrees Fahrenheit). It is also very viscous, meaning that it flows slowly and does not easily change shape.
Lava can be classified into two main types: pahoehoe and aa. Pahoehoe lava is smooth and often resembles rope or tangled hair. Aa lava is rough and jagged with a blocky texture. Each type of lava has a different flow rate; pahoehoe flows more slowly than aa.
Lava flows are dangerous because they can move quickly and without warning. They can also be very hot, making them capable of causing burns or even setting fire to anything in their path. In addition, the gases emitted by lava flows can be poisonous. For these reasons, it is important to stay away from any active volcanoes or areas where lava flows are known to occur.