(public display, Geology Department, Wittenberg University, Springfield, Ohio, USA) ----------------------------------- Igneous rocks form by the cooling & crystallization of hot, molten rock (magma & lava). If this happens at or near the land surface, or on the seafloor, they are extrusive igneous rocks. If this happens deep underground, they are intrusive igneous rocks. Most igneous rocks have a crystalline texture, but some are clastic, vesicular, frothy, or glassy. Volcanic tuffs are solidified ash deposits - they form by explosive volcanic eruptions, as do volcanic breccias. Volcanic tuffs lack the abundance of large, angular grains present in volcanic breccias (although I
Minerals, Free Full-Text
Exploring for structurally concealed Carlin-type mineralization: A
Welded tuff (western USA), (public display, Geology Departm…
Search U.S. Geological Survey
USGS: Geological Survey Bulletin 1161-D (Stratigraphy)
Geosciences, Free Full-Text
James Starnes, RPG - Division Director, Surface Geology Division
Materials, Free Full-Text
Volcaniclastic rock and sediment: Mineral information, data and
Distinguishing and correlating deposits from large ignimbrite
Tuff - Igneous Rocks
Search U.S. Geological Survey
NPS Stratotype Inventory - Geology (U.S. National Park Service)
Volcanic Ash, Tephra Fall, and Fallout Deposits (U.S. National