Volcanic plateau facts for kids
A volcanic plateau is a large, flat area of land that was created by volcanic activity. Imagine huge amounts of lava or volcanic ash piling up over a long time. This forms a high, flat surface that looks like a giant table. There are two main types: lava plateaus and pyroclastic plateaus.
How Lava Plateaus Form
Lava plateaus are made from very runny, liquid basaltic lava. This lava flows out during many eruptions that happen one after another. These eruptions are usually quiet, not explosive. This is because the lava is very fluid and doesn't have much trapped gas.
The lava can flow out from long cracks in the ground called fissures or rifts. Sometimes, it comes from giant eruptions that happened a long time ago, creating huge flood basalts. Over time, many layers of lava flows cover the original land. This builds up to form a plateau. These plateaus can include lava fields, small cone-shaped hills called cinder cones, and large, gently sloping volcanoes called shield volcanoes.
Sometimes, a lava plateau can even be part of a single, huge volcano. For example, Level Mountain in British Columbia, Canada, is a massive shield volcano. It covers an area of about 1,800 square kilometers (690 square miles).
Many volcanic plateaus exist around the world. The Columbia River Plateau in the United States is a well-known example on land. There are also huge volcanic plateaus under the ocean, like the vast Ontong Java Plateau. Long ago, during the Paleogene period, a massive basaltic plateau called the Thulean Plateau covered a huge area in the northern Atlantic Ocean. Scientists believe it later broke apart to form parts of the ocean floor we see today.
How Pyroclastic Plateaus Form
Pyroclastic plateaus are formed by massive pyroclastic flows. These are fast-moving currents of hot gas and volcanic rock fragments. The ground under these plateaus is made of pyroclastic rocks. These rocks include agglomerates (larger chunks), tephra, and volcanic ash. The ash often gets cemented together to form a rock called tuff.
These plateaus are also sometimes called ignimbrite plateaus. An example is the Shirasu-Daichi plateau, which covers most of southern Kyūshū, Japan. Another example is the North Island Volcanic Plateau in New Zealand.
