1st Quarter Summative Test in Earth Science 12

Magma and Rock Formation

• Formation of magma typically begins at the junctions between mineral grains.
• As magma crystallizes, it evolves by becoming more felsic and more viscous as mafic minerals crystallize out.
• The terms "younger" and "older" relate to the relative dating of geological formations.
• Intrusive rocks generally possess an age different from that of surrounding rocks, and specific patterns may indicate their formation history.

Geological Processes

• Faulting and magma intrusion affect rock formations differently; specific relationships exist between these processes.
• Arrangement of rocks can indicate their chronological order, from youngest to oldest.
• Isotopes with short half-lives are ineffective for dating ancient rocks due to their rapid decay.

Rock Composition and Properties

• Parent and daughter atoms undergo transformations after the first half-life during radioactive decay.
• Earth’s characteristics enabling life exclude certain factors like distance from the sun or presence of water.
• Density is crucial for understanding a planet's surface gravity; Earth is denser than many celestial bodies.

Mineral Properties

• Rocks are composed of building blocks known as minerals.
• Atoms are fundamental units of matter, which cannot be divided by ordinary chemical processes.
• Streak refers to the color of mineral powder when rubbed on unglazed porcelain.
• The tendency of minerals to cleave along flat surfaces is known as cleavage.

Types of Rocks and their Formation

• Igneous rocks result from the solidification of magma.
• The geological cycle involves formation, destruction, alteration, and reformation of rocks.
• Sedimentary rocks form through processes of weathering and erosion.

Magma Characteristics and Behavior

• The distinction between magma and lava lies primarily in their locations; magma is underground, while lava is on the surface.
• Various statements regarding magma include that it forms when rocks melt, and temperatures of magma commonly exceed 1000 degrees Celsius.
• Bowen's Reaction Series illustrates the development of mineralogy in cooling magma, primarily decreasing temperature.

Earth's Structure and Composition

• The Earth's mantle consists mostly of solid rock, interspersed with pockets of liquid rock.
• Mafic eruptions are less explosive than felsic eruptions due to the higher temperature of mafic magma, allowing gases to remain dissolved.
• Fractionation refers to the segregation of minerals during cooling, affecting the composition of the remaining magma.

Planetary Atmospheres

• Earth's atmosphere is composed of approximately 77% Nitrogen, 21% Oxygen, and 1% Argon, highlighting its unique characteristics in the solar system.

Additional Study Notes

• Planet classifications vary based on size, reinforcing the diversity of celestial bodies.