Earth Science Lessons 1-2

Igneous rock

Formed by the cooling/solidification of magma or lava.

Intrusive igneous rock

Forms from slowly cooling and solidification of magma.

Extrusive igneous rock

Forms from rapidly cooling and solidification of magma.

Rock

Naturally occurring coherent aggregate of minerals such as natural glass/organic matter.

Pyroclastic igneous rock

Form from consolidation of particle erupted by explosive volcanic activity via lithification, hybrid of igneous and sedimentary process.

Sedimentary rocks

Formed through the compaction and cementation of sediments.

Clastic formation

Form from the cementation of sediments that have been deposited, buried, and compacted over a long period of time.

Crystalline

Formed when they precipitate out from solution.

Bioclastic formation

Form from the compaction and cementation of plant and or animal remains.

Hint: ___ formation

Metamorphic rocks

Rocks formed from other rocks. They are sedimentary or igneous rocks that have undergone changes as a result of extreme pressure and heat.

Regional metamorphism

Dominant altering factor if pressure, usually due to tectonic activity. The flat and elongated mineral components of the preexisting rocks react by aligning perpendicular to the axis of the pressure. This result in a layered or banded appearance in the rocks called foliation, therefore creating foliated metamorphic rocks.

Contact metamorphism

Dominant altering factor if heat, forms non-foliated metamorphic rock.

Light-colored igneous rock

Indicates a felsic composition. White, gray, tan, and pink.

Dark-colored igneous rock

Indicate a mafic/ultramafic composition. Black & brown.

Intermediate composition

Have intermediate color such as gray or consisting of equal parts dark and light minerals.

Chemical sedimentary rocks

Precipitation of minerals from ions in solution.

Clastic sedimentary

Formed from Lithification. May also be classified as clay, sand and gravel. Examples are quartz, feldspar, and clay.

Bioclastic sedimentary

Formed as a result of accumulation or organic material or biological activity. It may contain remnants of plants. Examples are bituminous coal, limestone, chalk, and coquina.

Clastic texture

Refined whether the shapes of the individual grains are angular or rounded.

Foliated (platy or elongated)

When the dominant agent of metamorphism is pressure.

Nonfoliated (Crystalline)

When the parent rocks are exposed with too much heat that induces recrystallization of existing minerals.

Rock cycle

Continuous process describing the transformation of the rocks through various stages through their lifetime.

Fossils

Recognizable remains or traces of ancient life that have been preserved by natural processes, form when living things die and then get buried quickly under sand, dirt, clay, or ash sediments.

Index fossils

Are any animal or plant preserved in the rock record of the Earth that is characteristic of a particular span of geologic time or environment.

Nicolas Steno

Danish geologist who created the laws of statigraphy in the mid-1600s. He found that solid particles settle from a fluid according to their relative weight or size. The largest, or heaviest, settle first, and the smallest, or lightest, settle last.

Superposition

New rock layers are always deposited on top of existing rock layers. Therefore, deeper layers must be older than layers closer to the surface.

Lateral Continuity

Rock layers extend laterally, or out to the sides. They may cover very broad areas, especially if they formed at the bottom of ancient seas. Erosion may have worn away some of the rock, but layers on either side of eroded areas will still “match up.”

Original Horizontality

Sediments were deposited in ancient seas in horizontal, or flat, layers. If sedimentary rock layers are tilted, they must have moved after they were deposited.

Cross-cutting Relationships

A principle of geology that states that the geologic feature which cuts another is the younger of the two features.

Relative dating

Determine whether the rock is older or younger than other rocks.

Absolute dating

Use radiometric dating techniques to determine how long ago the rock formed in the exact number of years.

Isotopes

Are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. When they become unstable, they are radioactive which releases energy, causing radioactive decay.

Half-life

The time needed for half of a sample of a radioactive substance to undergo radioactive decay.

Geological time scale

System of chronological measurement that relates stratigraphy to time, describes the timing and relationships between events that have occurred throughout Earth’s history. Developed in the 1800s using the relative dating of rocks.

Precambrian

It is 87% of Earth’s History. Any information from this time period is sketchy. Erosion has destroyed most of the rocks and fossils, any fossils that have survived are rare and simple in structure.

Hadean Eon

• “Hell-like”/Hellfire & Brimstone

• From 4600 – 3800 Mya

• The Solar System is still forming through planetary bombardment

• Sun was only 70% as bright

• Massive volcanism created the young atmosphere which was probably made up of CO2 (carbon dioxide), H2O (water), CH4, (Methane) & NH3 (ammonia)

• No fossils were found during this time.

• Formation of the Moon

Archean Eon

• From 3800 – 2500 Mya

• Surface of the earth turns from molten to solid rock

• Oceans formed from water vapor condensation

• Oldest rocks known have been dated to this eon

• Potentially the first simple bacteria/algae fossils were found

• Noxious atmosphere was very depleted of oxygen

• Continents begin to form from small islands

Proterozoic Eon

• “First life”

• From 2500 – 570 Mya

• Largest Eon (~2B yrs total)

• Bacteria enriches the atmosphere with oxygen — ozone layer forms too (good)

• Supercontinent Rodinia formed around 800 Mya

• Simple multi-cell fossils were discovered

• Eukaryotic cell fossils were also observed

• Due to extensive glaciations there was an ice age that

  covered the entire Earth -- “Snowball Earth”

Phanerozoic Eon - “Visible Life”

• A great diversity of land and ocean organisms was observed

• Fossil record indicated complex organisms thrive during this time.

• Several mass extinctions were also observed.

• We are still currently living in the ____.

Hint: This one has quotation marks.

Paleozoic Era - “Cambrian Explosion”

• It spans from 570 – 245 Mya

• It is divided into 7 Periods

• Cambrian, Ordovician, Silurian, Devonian, Mississippian,

  Pennsylvanian, Permian

• At the beginning of the Cambrian, the fossil record goes through an exponential increase in diversity and complexity

• The supercontinent Pangaea was formed.

Ordovician - Cambrian Periods

• “Age of Invertebrates”

• The sea was alive with life

Hint: Starts with O.

Devonian - Silurian Periods

• “Age of Fishes”

• Fishes were the dominant species, the sea was flourishing with life, land was starting to develop, and the Pangea was starting to break up.

Mississippian-Pennsylvanian-Permian Periods

• “Age of Amphibians”

• Land continues to develop into lush forests.

• Aquatic animals started to invade and inhabit the land.

Mesozoic - Age of Reptiles

• Has 3 periods from 245-66 Mya

  • Triassic

  • Jurassic

  • Cretaceous

• Pangea begins to break apart to form Laurasia and Gondwanaland and eventually the other continents.

• Warmer climates dominated.

• Gymmnosperms (non-flowering, naked seed) appear and become the dominant plant.

Cenozoic Era - Age of Mammals

• Composed of 2 periods spanning from 66 Mya to present day

  • Tertiary

  • Quatemary

• 7 Epochs are contained within the two periods

  • Paleocene, Eocene, Oligocene, Micocene, Pliocene, Pleistocene, & Holocene (where we are)

Boundary events

How scientist explain the changes in life forms which are obvious in the record of fossil rocks.

Anthropocene Epoch

At present some scientists are saying that we have come to the dawn of a new time period. It has been proposed that we are no longer in the Holocene but already in the ____.