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 rock

    4.  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.