Overview
This lecture covers key Earth Science Regents concepts, including density, mapping, rock types, weathering, plate tectonics, atmospheric conditions, and climate, emphasizing definitions, foundational processes, and exam-relevant relationships.
Density & Physical Properties
- Density is how tightly packed molecules are.
- As temperature increases, density decreases due to molecular expansion.
- As pressure increases, density increases as molecules get closer.
- Objects have the same density regardless of size.
Mapping & Coordinates
- Latitude lines run horizontally, measuring distance north or south of the Equator.
- Longitude lines run vertically, measuring east-west of the Prime Meridian.
- The altitude of Polaris equals an observer’s northern latitude.
- Time zones are 15° of longitude apart, equaling 1 hour difference.
- Moving west makes time earlier; moving east makes time later.
- Closer isolines mean steeper gradients on maps.
- Water flows downhill, opposite the bends in contour lines.
Minerals, Rocks, & Weathering
- Calcite and limestone react with acid.
- Properties of minerals depend on atomic arrangement.
- Rocks are classified by how they formed: igneous (cooling magma), sedimentary (compaction/cementation), metamorphic (heat/pressure).
- Igneous rocks: large crystals (slow cooling), small crystals (fast cooling), vesicular (gas pockets).
- Sedimentary rocks: formed from particles, may contain fossils.
- Metamorphic rocks: formed by heat and pressure; look for foliation.
- Smaller particles weather faster due to higher surface area.
- Warm, moist climates favor chemical weathering; cold, moist climates favor physical weathering.
Erosion, Deposition, & Landscapes
- Streams form V-shaped valleys; glaciers form U-shaped valleys.
- Fastest stream velocity is on the outside of bends; slowest on the inside, where deposition occurs.
- Gravity and glaciers leave unsorted, unlayered deposits; wind and water deposits are sorted.
- Deltas form where rivers slow and deposit sediment entering the ocean.
Plate Tectonics & Earth's Structure
- Plate tectonics are caused by convection currents in the mantle (asthenosphere).
- Earthquakes and volcanoes are concentrated at plate boundaries.
- Ocean crust is dense, young, thin, and basaltic; continental crust is thick, old, and granitic.
- Outer core is liquid—S waves can't travel through it.
- Plate boundaries: divergent (apart), convergent (together), transform (sliding).
- P waves are faster and travel through solids and liquids; S waves move slower and only through solids.
Geologic Time & Fossils
- Law of superposition: bottom layers are oldest in undisturbed strata.
- Contact metamorphism shows interactions between intrusion and surrounding rock.
- Index fossils spread widely but lived briefly; unconformities indicate missing geologic time.
- Radioactive half-life is constant.
- Carbon-14 dates recent remains; Uranium-238 dates ancient rocks.
Weather & Climate
- Barometers measure air pressure; anemometers measure wind speed; wind vanes show direction.
- Wind is caused by air pressure differences and flows high to low pressure.
- High pressure means clear weather; low pressure brings clouds and rain.
- Coriolis effect deflects winds rightward in the Northern Hemisphere.
- Humidity and dew point are measured with a sling psychrometer.
- Clouds form when warm air rises, cools, and condenses at the dew point.
- US weather generally moves west to east.
- Warm air rises (less dense); cold air sinks (more dense).
- Hurricanes form over warm oceans, weaken over land or cool water.
Water Cycle & Soil
- Infiltration occurs on permeable, unsaturated, gentle, unfrozen land; runoff when impermeable, saturated, steep, frozen.
- Porosity is the percentage of empty space in soil and doesn't depend on particle size.
- Permeability measures water flow through soil; larger particles increase permeability.
- Capillarity is upward water movement; decreases with larger particles.
Key Terms & Definitions
- Density — mass per unit volume, indicating compactness.
- Latitude/Longitude — geographic coordinates for location.
- Polaris — North Star, used to determine latitude in the Northern Hemisphere.
- Isolines — lines of equal value on maps (e.g., elevation, pressure).
- Igneous/Sedimentary/Metamorphic — three rock types, based on formation.
- Weathering — breakdown of rocks; chemical or physical.
- Delta — landform where river meets ocean and deposits sediment.
- Convection Current — movement in mantle causing plate tectonics.
- Half-life — time for half a radioactive substance to decay.
- Barometer/Anemometer/Wind Vane — instruments for air pressure, wind speed, and direction.
- Coriolis Effect — deflection of moving fluids due to Earth’s rotation.
Action Items / Next Steps
- Review ESRT for identifying rocks and interpreting maps.
- Practice calculating half-life using provided charts.
- Prepare flashcards for key terms and rock identification features.