91Ó°ÊÓ

Identify the igneous rock textures described by each of the following statements. a. Openings produced by escaping gases b. The texture of obsidian c. A matrix of fine crystals surrounding phenocrysts d. Consists of crystals that are too small to be seen without a microscope e. A texture characterized by rock fragments welded together f. Coarse grained, with crystals of roughly equal size g. Exceptionally large crystals, most exceeding 1 centimeter in diameter

A common misconception about Earth's upper mantle is that it is a thick shell of molten rock. Explain why Earth's mantle is actually solid under most conditions.