ASVAB CampEarth Science flashcards
8 cards with the formulas, rules and traps from this lesson. Answer in your head, then flip to check.
Term · 1/8
Divergent, convergent and transform boundaries: how do plates move at each?
Divergent: plates separate, making new crust at mid-ocean ridges and rift valleys. Convergent: plates move together, causing subduction trenches, volcanic arcs or mountains. Transform: plates slide sideways past each other (San Andreas).
Common trap · 2/8
Do tectonic plates float on an ocean of liquid magma?
No. The mantle is mostly solid rock that deforms and flows very slowly. The rigid lithosphere (crust plus uppermost mantle) moves over the weak but solid asthenosphere. Only the outer core is liquid.
Rule · 3/8
How do you tell igneous, sedimentary and metamorphic rocks apart by how they form?
Igneous: magma or lava cools and solidifies. Sedimentary: sediment is deposited, compacted and cemented. Metamorphic: existing rock changes under heat and pressure without melting (limestone to marble).
Term · 4/8
Weathering, erosion and deposition: what does each do?
Weathering breaks rock down in place (frost wedging, dissolving). Erosion carries the loose material away by water, wind, ice or gravity. Deposition is where the material settles, such as a delta at a river mouth.
Term · 5/8
Earthquake focus versus epicenter?
The focus (hypocenter) is the underground point where rupture begins. The epicenter is the spot on the surface directly above the focus. Neither is automatically where shaking is strongest.
Fact · 6/8
How do P waves and S waves differ?
P (primary) waves are compressional, arrive first and travel through solids and liquids. S (secondary) waves are shear waves that cannot pass through liquids, which is evidence for a liquid outer core.
Common trap · 7/8
What mainly causes Earth's seasons?
Earth's axial tilt of about 23.4 degrees, which changes the Sun's angle and day length. It is not the changing Earth-Sun distance. The two hemispheres have opposite seasons.
Formula · 8/8
How much of a radioactive parent remains after a number of half-lives?
Halve the amount once per half-life: remaining = start x for n half-lives. 80 units become 40, then 20 (25%) after two half-lives; the sample never simply drops to zero.