What is the difference between the asthenosphere and the stiffer mantle?
Regional SpecificsWhat is the difference between asthenosphere and mantle? What is the difference between mantle and asthenosphere? Below the Moho, the mantle is characterized by peridotite, a rock mostly made up of the minerals olivine and pyroxene. The asthenosphere is the denser, weaker layer beneath the lithospheric mantle. What is the stiffer mantle? Stiffer Mantle. THE
When did the Phanerozoic eon begin?
Regional Specificsapproximately 541.0 million years agoapproximately 541.0 million years ago. It is predated by the Precambrian eons. The Phanerozoic began with the Cambrian Explosion, which was the massive biodiversification of multicellular organisms that developed in the late Precambrian. When did the Phanerozoic begin when did it end? Phanerozoic Eon, the span of geologic time extending about
What type of fossils are found in Virginia?
Regional SpecificsPelecypods, also called bivalves, are soft-bodied animals that secrete a hard shell with two sides, such as an oyster or clam. Pelecypods are abundant in the Cenozoic sedimentary deposits of Virginia’s Coastal Plain. Virginia’s state fossil is the bivalve Chesapecten jeffersonius, pictured here. What are most of the fossils found in Virginia of? Fossils can
What are the three laws of relative dating?
Regional SpecificsThe Principle of Original Horizontality states that all rock layers were originally horizontal. The Law of Superposition states that younger strata lie on top of older strata. The Principle of Cross-Cutting Relationships states that intrusions and faults that cut across rock are necessarily younger than that rock. What are the 3 basic principles of relative
What type of lava does a composite volcano have?
Regional SpecificsAcidic lavaAcidic lava, which is very viscous (sticky). Steep sides as the lava doesn’t flow very far before it solidifies. Alternate layers of ash and lava. What type of lava flow does a composite volcano have? Stratovolcanoes show interlayering of lava flows and typically up to 50 percent pyroclastic material, which is why they are
What rocks are devoid of fossils?
Regional SpecificsIgneous rocks form from molten rock, and rarely have fossils in them. Metamorphic rocks have been put under great pressure, heated, squashed or stretched, and fossils do not usually survive these extreme conditions. Which rock is devoid of fossils which hinders correlation of rocks? Most Mesozoic rocks are devoid of fossils; consequently this is the