I enjoyed seeing the interesting Volcanic rocks on the bank of the Nisqually River. Even though they originate from the same mountain, the colors are different depending on the minerals or elements they contain and how quickly the magma cooled. Red in the rock indicates large amounts of iron.
The kinds of igneous rock associated with with volcanoes include: basalt, andesite, dacite and rhyolite. Basalt comprises the majority of the Earth's crust and is the most common type of rock on earth. This rock is extrusive, meaning it formed from magma in the Earth's mantle, was released as lava and cooled fairly quickly at the surface. Geologists examine the size of the crystals in these rocks, the faster the rock cooled, the smaller the crystals.