Earth and Space Science (MTEL 74): One Integrated Field
Earth and Space Science (74) is tested as a single broad domain on this MTEL subject-matter exam, so items move from Earth's interior to the Solar System without warning. Expect selected-response questions that ask you to interpret data - seismic records, station models, radiometric ratios, star charts, cross-sections - plus open-response prompts that ask you to explain a process and defend it with evidence from the stimulus.
Core rules and concepts
- Earth's interior: crust, mantle, liquid outer core (creates the S-wave shadow zone roughly 103°–143° from the epicenter), solid inner core. Pressure, temperature, and density all rise with depth.
- Plate tectonics: divergent boundaries make new crust at ridges; convergent boundaries give subduction, trenches, arc volcanism, or continental-collision fold belts; transform boundaries are strike-slip. Hotspot chains record plate motion and direction.
- Rocks: igneous texture records cooling rate (coarse = slow, intrusive); sedimentary rocks record stratification, cross-bedding, and fossils; metamorphic rocks record directed pressure as foliation.
- Surface processes: weathering breaks rock in place; erosion transports the debris; deposition sorts it by grain size and rounding.
- Atmosphere and weather: rising air cools adiabatically to the dew point and condenses; fronts mark air-mass boundaries; the Coriolis effect deflects direction, never speed.
- Astronomy: seasons come from the 23.5° axial tilt, not distance; Moon phases come from orbital geometry; eclipses require alignment near the orbital nodes.
Worked example
A granite sample holds 1/8 the parent isotope of fresh rock; the parent's half-life is 700 million years. Each half-life halves the parent, so 1/8 = (1/2)³, or three half-lives. 3 × 700 Myr = 2.1 billion years. Reason from the fraction of parent remaining first, then multiply - do not start from a daughter-to-parent ratio unless the prompt gives one.
Traps that cost marks
Weathering is not erosion; a normal fault has the hanging wall moving down (extension); the Coriolis effect never changes wind speed; S-waves cannot cross a liquid; and cleavage (flat planes from crystal structure) is not the same as fracture.