Evidence of Change Mind Map
← Evidence of ChangeHow rock layers, fossils, and ice cores record Earth’s history, how species change or die out over many generations, and how constructive and destructive processes shape the land.
- geologic recordThe history of Earth that is preserved in rock layers and fossils.The geologic record shows that Ohio was once under a sea.
- law of superpositionThe rule that in undisturbed rock layers, the oldest layer is at the bottom and the youngest is at the top.By the law of superposition, the bottom layer formed first.
- relative ageWhether a rock or event is older or younger than another, without an exact number of years.We found the relative age of each layer by its position.
- crosscutting relationshipsThe rule that a feature cutting across rock layers is younger than the layers it cuts.Crosscutting relationships tell us the fault came last.
- igneous intrusionMagma that pushed into other rock and hardened underground. It is younger than the rock it cuts.The igneous intrusion cuts across three older layers.
- faultA crack in Earth’s crust where rocks have moved.The layers on each side of the fault no longer line up.
- unconformityA gap in the rock record caused by erosion or a time when sediment was not deposited.The wavy line in the cliff is an unconformity.
- absolute ageThe actual age of a rock or fossil in years.Scientists measured the absolute age of the ash layer.
- radiometric datingFinding a rock’s age in years by measuring how much of a radioactive element has changed.Radiometric dating showed the rock was 450 million years old.
- index fossilA fossil of a species that lived for a short time over a wide area, used to date rock layers.Trilobites are a useful index fossil.
- geologic time scaleA timeline that divides Earth’s history into eras and periods.Dinosaurs appear late on the geologic time scale.
- ice coreA long tube of ice drilled from a glacier that holds clues about past climate.Air bubbles in the ice core show past carbon dioxide levels.
- paleoclimateThe climate of a place long ago.Coal layers tell us the paleoclimate was warm and swampy.
- fossilThe preserved remains or traces of a living thing from long ago.We found a shell fossil in the limestone.
- fossil recordAll the fossils found so far and what they tell us about life in the past.The fossil record shows that life has changed over time.
- transitional formA species that shows features partway between an older group and the newer group that came from it.A fossil of a fish with leg-like fins is a transitional form.
- common ancestorAn earlier species that two or more later species came from.Horses and zebras share a common ancestor.
- speciesA group of organisms often defined by their ability to breed and produce fertile offspring; other evidence is needed for fossils and asexual organisms.Lions and tigers are different species.
- variationDifferences among objects, individuals, conditions, or measurements, including traits within a population.Variation in beak size helped some birds survive.
- diversityThe number of different kinds of living things in an area.Coral reefs have great diversity.
- adaptationAn inherited characteristic that helps survival or reproduction in a particular environment.Thick fur is an adaptation to cold weather.
- natural selectionA process in which inherited traits that aid survival and reproduction become more common in a population over generations.Natural selection favored moths that blended in with tree bark.
- evolutionChange in inherited characteristics of populations over generations.Fossils show the evolution of whales from land animals.
- extinctionWhen every member of a species has died.An asteroid led to the extinction of most dinosaurs.
- constructive processA natural process that builds up land, such as a volcano erupting or sediment piling up.A lava flow is a constructive process that adds new land.
- destructive processA natural process that wears away or destroys land, such as erosion or a landslide.A landslide is a destructive process.
- erosionThe moving of rock and soil from one place to another by water, wind, ice, or gravity.Erosion by the river carved a canyon.
- depositionThe dropping of rock pieces in a new place after they have been moved.Deposition at the river mouth built a delta.
- upliftThe raising of land to a higher level by forces inside Earth.Uplift raised old sea-floor rock into mountains.
- glacierA huge mass of ice that moves slowly over land.A glacier flattened much of northern Ohio.
- landformA natural shape on Earth’s surface, such as a mountain, valley, or plain.A canyon is a landform made by a river.
- flood plainFlat land beside a river that is covered with water when the river floods.Rich soil collects on the flood plain.
- deltaA fan of sediment that builds up where a river enters a lake or ocean.The Mississippi River ends in a large delta.
- elevationHow high a place is above sea level.Campbell Hill has the highest elevation in Ohio.
- topographic mapA map that uses lines to show the shape and height of the land.The topographic map showed a steep hill.
- contour lineA line on a map that connects points at the same height.Contour lines close together mean a steep slope.
- aerial mapA map made from photos taken from high above the ground.The aerial map showed the new houses by the river.