Observations and Identification of Rocks Types on Island. Use the photographs and descriptions provided below to identify the type of igneous present. Then, infer what kind of eruption probably formed this rock. Examine the photographs below and read the key characteristics listed for each rock type. Rock 2 Rock 1 Rock 3 Key characteristics: dark gray, glassy with Key characteristics: large, flattened pieces Key characteristics: angular pieces of gray small vesicles, has bands (flow bands) of light-colored pumice, matrix around the volcanic rocks in a matrix of powdery produced by flow when the rock was pieces contains hard compacted ash and volcanic ash and smaller rock fragments, molten, felsic composition, pumice, and broken crystals of quartz. larger pieces are dark gray, glassy, vesicular, and somewhat banded. Rock type (circle one): (a) basalt, Rock type (circle one): (a) basalt, Rock type (circle one): (a) basalt, (b) rhyolite or obsidian, (e) welded tuff, (b) rhyolite or obsidian, (c) welded tuff, (6) rhyolite or obsidian, (c) welded tuff (d) volcanic broccia (d) volcanic breccia (d) volcanic breccia Style of eruption (circle one): (a) eruption Style of eruption (circle one): (a) eruption Style of eruption (circle one): (a) eruption of a low-viscosity, basaltic lava flow. (b) of a low-viscosity, basaltic lava flow, (b) of a low-viscosity, basaltic lava flow, eruption of high-viscosity lava in a dome, eruption of high-viscosity lava in a dome, (b) eruption of high-viscosity lava in a (c) dome collapse that forms volcanic (c) dome collapse that forms volcanic dome, (c) dome collapse that forms breccia, (d) eruption of a pyroclastic flow breccia, (d) eruption of a pyroclastic flow volcanic breccia or eruption of a that forms a thick and hot deposit, (e) slow that forms a thick and hot deposit, (e) slow pyroclastic flow, (d) slow settling of ash settling of ash from a tall eruption column. settling of ash from a tall eruption column, from a tall eruption column, forming a forming a nonwelded tut. forming a nonwelded tuff. nonwelded tuft
