Earth History Vocabulary
1. rock: a solid mixture of crystals of one or more minerals.2. rock cycle: the process by which one rock type changes into another.3. composition: the makeup of a rock4. texture: the sizes, shapes, and positions of the grains that a rock is made of.1. observation: information gathered directly by using one or more of the five senses.
2. inference: a logical conclusion based on observations and past experience.
3. mountain: high, uplifted area with steep slopes.
4. canyon: a v-shaped valley eroded by a river.
5. dune: a mound, hill, or ridge of windblown sand.
6. valley: a low area between hills and mountains, often where a river flows.
7. meander: a curve or loop in a river.
8. plain: nearly level area that has been eroded or where material has been deposited.
9. floodplain: the land that gets covered by water from a stream or river during a flood.
10. beach: gently sloping shore next to a body of water washed by waves or tides.
11. plateau: a nearly level area that has been uplifted.
12. delta: a fan-shaped deposit at the mouth of a river.
13. weathering: the breakdown of rock into smaller and smaller pieces by mechanical or chemical means.
14. mechanical weathering: the breakdown of rock into smaller pieces by physical means (water, wind, ice, abrasion).
15. chemical weathering: the chemical breakdown of rocks and minerals into new substances.
16. erosion: the removal and transport of material by wind, water, or ice.
17. deposition: the process by which material is dropped or settles.
18. differential weathering: the process by which softer, less weather-resistant rocks wear away, leaving harder, more weather-resistant rocks behind.
19. abrasion: the grinding and wearing down of rock surfaces by other rock or sand particles.
20. principle of uniformitarianism: processes of erosion and deposition that happen today happened throughout geological history.
21. law or original horizontality: most sediments, when originally formed, were laid down horizontally.
22. absolute dating: establishing the age of an object by determining the number of years it has existed.
23. relative dating: determining whether an object or event is older or younger than other objects or events.
24. superposition: a principle that states younger rocks lie above older rocks in undisturbed sequences.
25. geologic column: an ideal sequence of rock layers that contains all the known fossils and rock formations on Earth arranged from oldest to youngest.
26. unconformity: a surface that represents a missing part of the geologic column.
27. geologic time scale: a scale that divides Earth's 4.6 billion year history into distinct intervals of time.
28. fossil: any naturally preserved evidence of life.
29. index fossil: a fossil of an organism that lived during a relatively short, well-defined time span, used to date the rock layers in which it is found.
30. rock: a solid mixture of crystals of one or more minerals.
31. rock cycle: the process by which one type of rock changes into another type of rock.
32. composition: the makeup of a rock.
33. texture: the sizes, shapes, and positions of the grains that a rock is made of.
34. igneous rock: rock that forms from the cooling of magma.
35. metamorphic rock: rock that forms when the texture and composition of preexisting rock changes due to heat and pressure.
36. sedimentary rock: rock that forms when sediments are compacted and cemented together.