British Sign Language Glossaries of Curriculum Terms

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BSL Geography Glossary - Igneous Rock - Lava Rock - Pumice Rock - Volcanic Dust or Ash Example

These rocks come from volcanoes. As the lava flows down the volcano’s slope, it cools and becomes hard like this rock. You can see how rough it is. This pale rock is slightly different, but it also comes from a volcano. In an eruption, the volcano sends out both lava and ash. The ash rises into the sky then settles all over the area. It is like lava, but has more air in it as it hardens to foam then rock. So pumice stone is a mixture of rock and volcanic ash. The reason it is so light is that the gas is mixed into it. In volcanic areas we also find ash called volcanic dust. These are all the products of volcanoes. If you find a rock like this, you know that in the area a long time ago there were active volcanoes where lava flowed.