What Does Igneous Rock Mean?
Igneous is derived from the word "ignis" meaning fire, and igneous rocks are formed as a result of hot liquid magma from inside the earth that solidifies on cooling. When the magma cools and solidifies beneath the earth's crust it is called intrusive igneous rock, while that which exits the crust and cools on the surface is called extrusive igneous rock. Trenchless construction methods like horizontal directional drilling (HDD) that bore holes beneath the earth's surface are likely to encounter igneous rocks, especially in areas where volcanic activity is prevalent or has occurred in the past.
