Definition - 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.
Trenchlesspedia explains Igneous Rock
Sedimentary, metamorphic and igneous rocks are the three major rock types, with many varieties in each type. Knowledge of the geology in the area where HDD, auger boring and other trenchless methods are to be used is important in completing a project successfully. This knowledge can be best achieved by conducting a geotechnical investigation of the route along which the pipeline is supposed to pass. Rock formations are challenging and require adequate equipment and appropriate drill bits to break through them.