EARTHSCI

Stratified Rocks

Rocks formed by the accumulation of sediments that get compacted and cemented over time.

Sedimentary Rocks

Another name for stratified rocks, formed from the compaction and cementation of sediments.

Law of Superposition

A principle stating that in undisturbed layers of rock, the oldest layer is at the bottom and the layers become progressively younger towards the top.

Relative Dating

A method used to determine the sequence of events without knowing their exact ages by studying layers of rocks.

Absolute Dating

A method that provides a precise age for rocks or fossils, often involving the decay of radioactive isotopes.

Radiocarbon Dating

A dating method used to determine the age of organic materials by measuring the amount of carbon-14 present.

Potassium-Argon Dating

A method used for dating older geological materials based on the decay of potassium into argon.

Index Fossils

Remains of organisms that lived during a specific, short time period and were geographically widespread, useful for dating rock layers.

Fossil Formation

The process that involves death, burial, preservation, mineralization, and exposure of an organism's remains over millions of years.

Permineralization

The process by which minerals from sediment seep into an organism's remains, replacing organic material and turning it into rock-like structures.

Geologic Time Scale

A system used by geologists to divide Earth's history into segments based on significant geological and paleontological events.

Eons

The largest time units in the geologic time scale, including Hadean, Archean, Proterozoic, and Phanerozoic.

Eras

Subdivisions of eons, such as Paleozoic, Mesozoic, and Cenozoic eras within the Phanerozoic eon.

Periods

Subdivisions of eras, including Cambrian, Ordovician, and Jurassic periods.

Epochs

Subdivisions of periods, such as the Paleocene and Holocene epochs.

Fossil Succession

A principle that allows the relative dating of rock layers based on the presence and evolution of fossil species.

Geological Processes

Natural processes, such as erosion and tectonic activity, that can expose fossils at the Earth's surface.

Organic Material

Remains of living organisms involved in the formation of fossils.

Decay Process

The breakdown of organic material after an organism's death, which can be slowed by conditions like lack of oxygen.

Clues about the Environment

Information gathered from the characteristics of rock layers that can indicate the environmental conditions during deposition.

Weathering

The process of breaking down rocks and minerals through various physical and chemical methods.

Exogenic Processes

Processes that occur at or near the Earth's surface, including weathering and erosion.

Mechanical Weathering

A type of weathering that physically breaks down rocks into smaller pieces without changing their chemical composition.

Chemical Weathering

The process that breaks down rocks and minerals through chemical reactions, resulting in new substances.

Abrasion

A form of mechanical weathering that occurs when rocks are broken down by being hit or impacted by other rocks, sand, or sediment.

Root Wedging

A process of mechanical weathering where roots grow into the cracks of a rock, causing it to break apart.

Frost Wedging

A type of mechanical weathering that occurs when water seeps into cracks in rocks and expands as it freezes, causing the rock to break.

Thermal Stress

A form of mechanical weathering caused by temperature changes, which causes rocks to expand and contract.

Oxidation

A chemical weathering process where oxygen reacts with iron in the rock, leading to the formation of iron oxide or rust.

Hydrolysis

A chemical weathering process in which hydrogen ions break down the chemical bonds in minerals, leading to their decomposition.

Carbonation

A chemical weathering process where water reacts with carbon dioxide to form carbonic acid, which weakens rocks.

Weathering Process

Involves the disintegration and decomposition of rocks, breaking them into smaller pieces.

Igneous Rocks

Rocks formed from melted rock deep within the Earth. Examples include quartz monzonite.

Sedimentary Rocks

Rocks formed from layers of sand, silt, dead plants, and animal skeletons. Examples include shale, limestone, sandstone, siltstone, and conglomerate.

Metamorphic Rocks

Rocks formed from other rocks that are changed by heat and pressure underground. Examples include quartzite, slate, gneiss, and marble.