Earth Science Combined

4.55 Ga

Age of the Earth

Radioactive Decay

The process in which unstable atoms emit energetic particles and gamma rays that heat the surrounding rock.

Planetary Differentiation

Due to gravitational force, denser substances such as iron (Fe) and nickel (Ni) sink toward the center in a process called ______ ______

Petrology

A branch of geology that deals with the origin, composition, structure, and classification of rocks

Stratigraphy

The study of rock layers (strata) and layering (stratifications).

Paleontology

-Studies the life that existed prior to, or sometimes the start of, the Holocene epoch (the current geologic epoch).

-Includes the study of fossils to determine how they have evolved and interacted with the environment.

Geological Time Scale

It represents the interval of time occupied by the geologic history of Earth.

Relative Dating

Places events or rocks in their chronological sequence or order of occurrence without knowing their actual age.

Original Horizontality

Sedimentary rocks are deposited due to gravity as horizontal or nearly horizontal layers. Any deviation from horizontality indicates that deformation occurs after the deposition.

Superposition

In the sequence of sedimentary rocks, the layer at the bottom of the sequence is oldest, and the successively higher levels are successively younger.

Cross-Cutting Relationship

Geologic features such as faults or igneous intrusion are younger than the rocks they cut across.

Inclusion

If rocks or rock fragments are included within another rock layer, the rock fragments must be older than the rock layer they were embedded in, therefore any time period can be recognized by its fossil content.

Igneous Intrusion

Where magma cut through other rock layers underground

Sill

Magma Intrusion (Horizontal)

When magma squeezes between horizontal layers of rock

Dike

Magma Intrusion (Vertical)

A slab of volcanic rock formed when magma forces itself across rock layers

Mammals

The last to evolve in the Animal Kingdom

Unconformities

A surface that corresponds with a gap in sedimentation resulting from nondeposition or erosion.

Angular Unconformity

The rocks below the unconformity are tilted. The rocks above it are parallel. The sequence follows an order of subsidence and deposition, uplift and tilt, erosion of the uplifted mountain, and then again by subsidence and deposition.

Disconformity

The beds above and below the surface are parallel. It can be recognized by correlating one area to another and discovering some strata are missing in one area.

Nonconformity

Intrusive igneous or metamorphic rocks are overlain by sedimentary rocks. This occurs if the metamorphic and intrusive igneous rocks undergo uplift erosion and then overlain sedimentary rocks.

Absolute Dating

Places actual ages of rocks and events. The method used is radiometric dating technique based on the decay rate of certain radioactive nuclides within fossils, rocks, and any artifact.

Half-life

The time required for half of the nuclei to undergo radioactive decay. The value is CONSTANT.

Isotope Ratio

The ratio of a naturally occurring radioactive isotope and its decay products

5,700 years

How long is a half-life?

Isotopes

Atoms of the same elements (same number of protons) but different number of neutrons.

Increases; decreases

(Half-Life) Time: ______; Amount: _______

Greenland

Where are the oldest rocks on Earth found?

They are 3.7-3.8 billion years old.

Apollo Mission

What took the oldest moon rocks which were found to be 4.4 to 4.5 billion years old.

70

How many dated meteorites have ages that range from 4.5 to 4.6 billion years old.

Radiometric Dating

the process of measuring the absolute age of geologic material by measuring the concentrations of radioactive isotopes and their decay products

also used in determining the ages of fossils, early human, and mineral deposits, recurrence rates of volcanic eruptions and earthquakes, magnetic field reversals, and age and duration of geologic events and processes.

Nicolas Steno

He created the Law of Superposition

Lithologic Similarity

rock type and characteristics

Fossils

key indicators of relative age as well as depositional environment.

Cavite

In this site, a 1970 ID card is found in the aluminum cans layer, indicating that the aluminum layer is 51 years old.

Laguna

In this site, a 1950 license plate is found on the tin cans layer, indicating that the tin layer is 71 years old as of 2021.

Age

Millions of years

Epoch

Tens of millions of years

Period

One hundred million years

Era

Several hundred million years

Eon

Half a billion years or more

Precambrian

The first 4.1 billion years of the geologic time scale.

Hadean

Considered as the "chaotic eon".

Hades; hell

Where did Hadean come from and what does it mean?

Late Heavy Bombardment

The Earth's surface was continuously bombarded by meteorites. The extremely hot mantle also caused severe volcanism due to the eruption of molten rocks onto the Earth's surface.

Archean

the time from 3,800 million years to 2,500 million years ago

It was defined by the oldest rock and the oldest fossils containing apex chert and stromatolite.

Continent formation began during this eon

Proterozoic

Era between 2.5 million to 544 million years ago. An oxygen-rich early atmosphere formed, sparking the Cambrian explosion of biodiversity.

It was considered the longest eon -- almost half the age of Earth.

Proterozoic

It was the time of great changes; oxygenation of the atmosphere, origin and diversification of life, and appearance of multicellular animal life.

More diverse forms of fossil.

Phanerozoic

This eon consists of three eras: Paleozoic, Mesozoic, and Cenozoic.

early Paleozoic

many fossils were found in layers of sedimentary rocks. It was the time when life greatly diversified.

Marine invertebrate probably lived near the shores of shallow water. Fossils of trilobites and brachiopods were found preserved in rocks.

middle Paleozoic

marine-life forms had developed shells. These shells formed beds of limestone and coral reefs.

The first animal to succeed in adapting itself to breathe air was an AMPHIBIAN that came out of the sea during the Devonian period.

middle Paleozoic

Land plants also began to develop during this period. Giant ferns and marsh plants provided food to land animals which increased in number.

late Paleozoic

This era showed the appearance of reptiles. At first, these animals looked much like their amphibian ancestors but had the great advantage of being able to lay eggs.

early Mesozoic

This era saw the formation of several continents. North America began to part from Europe, and probably, South America and Africa began to drift apart.

New bodies were formed. Great changes in plant and animal life occured.

Dinosaurs

The largest creatures that existed during the Mesozoic era.

These were believed to be descendants of the primitive reptiles that had survived from the Paleozoic era.

Cenozoic

In this era, mountains were uplifted and new life forms began to appear. The volcanic activity that widespreadly occurred formed immense flows of lava and basalt.

Ice Age

Age where glaciers covered the northern hemisphere, and is believed to have lasted for about two million years.

Fossil

A remnant or trace of organisms of a past geologic age.

William Smith

He discovered the each rock formation in the canal excavations on the coal mines he worked on contained fossils.

Principle of Fossil Succession

States that fossilized organisms succeed one another in a definite and determinable order; therefore, any time period can be recognized an Age of Fishes, an Age of Reptiles, and an Age of Mammals.

Index Fossils

Associated with a particular span of geologic time. They determine the date of the layer where they are found.

True form fossils

Formed when the entire animal or plant are trapped and preserve in ice, tar, or other materials that prevent decay.

Mold fossils

Hollow impressions of a living thing in a rock. This reflects the shape and surface marking of the organisms

Cast fossils

Formed when mold fossils are filled with mineral that hardens, forming a replica of the original fossil

Trace fossils

Impressions on rocks that show certain animal activities. This type of fossil can be footprints, eggs, droppings, or nests of animals.

Ichnofossils

Another name for trace fossils

Galaxy

defined as a gravitationally-bound system of stars, interstellar gas, dust, and dark matter.

170 billion

How many galaxies are in the observable universe?

Vortex Theory

Theory that proposed that the Solar System formed into bodies with nearly circular orbits, because of the whirlpool-like motion of the pre-solar materials.

Rene Descartes

a French mathematician and physicist, was one of the first proponents of a model on the origin of the Solar System.

Proposed the Vortex Theory

Collision Theory

Theory that proposed that the planets were formed by the collision of the sun with a giant comet. The resulting debris formed into planets that rotate in the same direction as they revolve around the sun.

George Buffon

a French naturalist in the eighteenth century who proposed the Collision theory

Tidal Theory

Theory that states that as a speeding massive star passed near the sun, it pulled off material due to gravitational attraction. The torn-off material subsequently condensed to form the planets.