NYSTCE Earth Science (162) flashcards

35 cards. Read the term and the definition here. The deck at the top of this page is optional.

Independent vs. dependent variable

The independent variable is the factor the experimenter deliberately changes. The dependent variable is the measured outcome that responds to it. Controlled variables are held constant to keep the test fair.

Hypothesis vs. theory

A hypothesis is a testable, falsifiable prediction about a specific situation. A scientific theory is a broad, well-supported explanation built from many lines of evidence, not a mere guess.

Percent error formula

Percent error equals the absolute value of measured minus accepted, divided by the accepted value, times 100. It expresses how far a measurement deviates from the true value.

Density and buoyancy rule

Density equals mass divided by volume. An object floats in a fluid when its density is less than the fluid's and sinks when greater. Water's density is 1.0 g/mL at 4 degrees Celsius.

Metric prefix conversions

Kilo means 10 to the third, centi 10 to the negative second, milli 10 to the negative third, micro 10 to the negative sixth, and nano 10 to the negative ninth. One milliliter equals one cubic centimeter.

Valid vs. reliable data

Validity means the investigation measures what it claims to measure. Reliability means repeated trials give consistent results. Increasing sample size and trials improves reliability but not necessarily validity.

Rate of change from graph

Rate of change equals the change in the dependent value divided by the change in time, which is the slope of a line graph. A steeper slope indicates a faster rate.

Reading a graduated cylinder

Read the volume at the bottom of the curved meniscus at eye level. Record all certain digits plus one estimated digit, since instrument precision limits how many digits are meaningful.

Cause of seasons

Seasons result from Earth's 23.5-degree axial tilt combined with revolution around the Sun, which changes the angle and duration of sunlight. Distance from the Sun is not the cause.

Solstice vs. equinox

At a solstice, around June 21 and December 21, the Sun reaches its highest or lowest noon position, giving the longest or shortest day. At an equinox, around March 21 and September 22, day and night are nearly equal.

Moon phase sequence

Phases cycle new, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, third quarter, waning crescent. They arise from the changing angle between Earth, Moon, and Sun.

Spring vs. neap tides

Spring tides are highest and occur at new and full moons when Sun and Moon align. Neap tides are lowest and occur at quarter moons when the two bodies pull at right angles.

Solar vs. lunar eclipse

A solar eclipse occurs at new moon when the Moon blocks the Sun from Earth. A lunar eclipse occurs at full moon when Earth's shadow falls on the Moon. Orbital tilt makes both rare.

Kepler's second law

A planet sweeps out equal areas in equal time intervals along its elliptical orbit. Therefore the planet moves fastest near perihelion, when it is closest to the Sun, and slowest near aphelion.

Terrestrial vs. Jovian planets

Terrestrial planets (Mercury, Venus, Earth, Mars) are small, dense, rocky, and few-mooned. Jovian planets (Jupiter, Saturn, Uranus, Neptune) are large, low-density, gassy or icy, ringed, and moon-rich.

Hertzsprung-Russell diagram

The H-R diagram plots stellar luminosity against temperature, hot blue stars on the left and cool red stars on the right. Main-sequence stars fuse hydrogen; red giants are cool but luminous; white dwarfs are hot but dim.

Evidence for the Big Bang

Key evidence includes the cosmic microwave background radiation, the redshift of distant galaxies showing expansion, and the observed abundance of light elements such as hydrogen and helium.

Light-year definition

A light-year is the distance light travels in one year, about 9.46 trillion kilometers. It measures distance, not time, and is used for interstellar and intergalactic scales.

Earth's compositional layers

By composition Earth has a thin silicate crust, a thick silicate mantle about 2,900 kilometers deep, and an iron-nickel core. By physical behavior the layers are lithosphere, asthenosphere, mesosphere, and core.

Three plate boundary types

Divergent boundaries pull plates apart, forming mid-ocean ridges and rift valleys. Convergent boundaries push plates together, forming trenches, volcanic arcs, and mountains. Transform boundaries slide past, producing strike-slip earthquakes.

Evidence for plate tectonics

Evidence includes matching continental coastlines and fossils, paleomagnetic striping on the seafloor, ocean floor age increasing away from ridges, and the worldwide distribution of earthquakes and volcanoes.

P waves vs. S waves

P waves are compressional and fastest, traveling through solids and liquids. S waves are shear waves, slower, and travel only through solids. Their arrival-time difference locates an earthquake epicenter.

Three rock types

Igneous rock forms from cooling magma or lava. Sedimentary rock forms from compacted and cemented sediments and often contains fossils and layers. Metamorphic rock forms from heat and pressure, often producing foliation.

Weathering vs. erosion

Weathering breaks rock down in place through physical processes like frost wedging or chemical processes like oxidation. Erosion then transports the broken material by water, wind, ice, or gravity.

Atmospheric layers and gases

The troposphere holds weather and cools with altitude. The stratosphere contains ozone and warms with altitude. Air is about 78 percent nitrogen and 21 percent oxygen.

High vs. low pressure

High-pressure systems bring sinking air, clear skies, and fair weather. Low-pressure systems bring rising air, cloud formation, and precipitation. Air flows from high toward low pressure.

Porosity vs. permeability

Porosity is the fraction of a material's volume made of pore space. Permeability is the ability to transmit water through connected pores. A material can be porous yet impermeable if pores are unconnected.

Principle of superposition

In an undisturbed sequence of sedimentary rock layers, the oldest layer lies at the bottom and the youngest at the top. This principle underlies relative dating of rock layers.

Cross-cutting relationships

A fault, igneous intrusion, or vein is younger than the rock layers it cuts across. Inclusions trapped inside a host rock are older than the rock containing them.

Types of unconformity

An angular unconformity is tilted eroded layers overlain by flat layers. A disconformity is an erosion surface between parallel layers. A nonconformity is sedimentary rock resting on igneous or metamorphic rock.

Radioactive half-life

A half-life is the time for half of a radioactive parent isotope to decay into daughter products. After n half-lives, the fraction of parent remaining is one-half raised to n.

Carbon-14 vs. uranium-238

Carbon-14 has a half-life near 5,730 years and dates organic remains up to about 50,000 years. Uranium-238 has a half-life near 4.5 billion years and dates ancient rocks and minerals.

Geologic time scale order

Time units from largest to smallest are eon, era, period, and epoch. Precambrian time covers about 88 percent of Earth history; the Phanerozoic eon includes Paleozoic, Mesozoic, and Cenozoic eras.

Index fossils and correlation

An index fossil comes from a species that was widespread but short-lived, so it marks a narrow time interval. Matching index fossils in separated rock layers lets geologists correlate those layers.

Uniformitarianism

Uniformitarianism, advanced by Hutton and Lyell, holds that present-day geologic processes acting over long periods explain past events. Catastrophism instead attributes some changes to sudden events like impacts.