Oceanic Ridges and Seafloor Spreading
Write a statement describing how spreading rates affect ridge topography. The greatest volume of magma (more than 60 percent of Earth’s total yearly output) is produced along the oceanic ridge … Read More
Correlation of Rock Layers
Explain how rocks of similar age that are in different places can be matched up. To develop a geologic time scale that is applicable to the entire Earth, rocks of … Read More
Sedimentary Rocks Represent Past Environments
Distinguish among three broad categories of sedimentary environments and provide an example of each. List several sedimentary structures and explain why these features are useful to geologists. Sedimentary rocks are … Read More
Contact metamorphism
The first mention of contact metamorphism/metamorphic phenomena dates back to the end of the eighteenth century when James Hutton observed that, the rocks surrounding a granitic body at Glen Tilt … Read More
Igneous Textures: What Can They Tell Us?
Identify and describe the six major igneous textures. The term texture is used to describe the overall appearance of a rock based on the size, shape, and arrangement of its … Read More
How Magmas Evolve
Describe how magmatic differentiation can generate a body that has mineralogy (chemical composition) that is different from its parent magma. Geologists have observed that, over time, a volcano may extrude … Read More
Gemstones and minerals;
Precious stones have been prized since antiquity. Although most gemstones are varieties of a particular mineral, misinformation abounds regarding gems and their mineral makeup.
Mineral Structures and Compositions
Distinguish between compositional and structural variations in minerals and provide one example of each. Many people associate the word crystal with delicate wine goblets or glassy objects with smooth sides … Read More
Metamorphic Zones
Explain how index minerals are used to establish the metamorphic grade of a rock body. In areas affected by metamorphism, geologists can observe the usually systematic variations in the mineralogy … Read More
Earth’s First Life
Describe some of the hypotheses on the origin of life and the characteristics of early prokaryotes, eukaryotes, and multicelled organisms. The oldest fossils provide evidence that life on Earth was … Read More