GEOL 1404 Review Outline- Exam 2

What percentage does the Proterozoic, Archaean and Hadean, take up compared to the Phanerozoic

The Proterozoic, Archaean, and Hadean together make up about 88% of Earth's history, while the Phanerozoic makes up the remaining 12%.

Plate Tectonics

When Earth first formed, plate tectonics were likely very different from what we see today, with a more solid crust.

When and where are the first valid known rocks from

The first rocks we have evidence of are from the Archaean era, around 4 billion years ago, found in places like Greenland and Western Australia.

Significance of Archean Igneous Rocks

Archean igneous rocks are significant as they provide evidence of the early formation and cooling of Earth's crust.

Greenbelt

A greenbelt refers to a belt of greenstone rocks, typically volcanic and sedimentary rocks associated with ancient oceanic crust.

Land Masses of Laurentia

Laurentia is composed of North America, Greenland, and parts of Scotland and Ireland.

Ophiolites

Ophiolites are sections of oceanic crust and mantle uplifted on land, providing insights into mid-ocean ridge processes.

Shield Platform and Craton

Stable areas of continental crust, shield platform, and craton have not been significantly deformed for billions of years.

First Valid Fossils

The first valid fossils are from around 3.5 billion years ago, found in Western Australia.

Wilson Cycle

Describes the cyclical process of continental drift, including supercontinent formation and breakup.

Single-Celled Organisms to Bacteria

Single-celled organisms need to metabolize organic molecules and reproduce to become living bacteria.

Grenville Orogeny

A major mountain-building event around 1 billion years ago in eastern North America.

Photosynthesis

The process by which plants and some bacteria convert light energy into chemical energy, producing oxygen.

Outgassing

Refers to the release of gases from Earth's interior, contributing to the early atmosphere.

Difficulty Studying Earth's Oldest Time

Early rock records have been destroyed or altered over billions of years, making it challenging to study Earth's oldest time.

Tectonically Active and Passive

Tectonically active regions experience frequent earthquakes and volcanic activity, while passive regions have stable crust. Parts of Laurentia were both during the Precambrian.

Atmosphere and Ocean Formation

Formed through processes like outgassing and water vapor condensation, likely not immediately habitable for life.

Accretion

The process of particles coming together to form larger bodies, such as planets.

Glacial Periods in the Proterozoic

Glacial periods occurred, particularly in regions like the Huronian Supergroup in North America.

Origin of Life

All life on Earth is believed to have originated from simple single-celled organisms.

First Fossil Organisms

Likely simple, single-celled organisms like bacteria and algae were the first fossil organisms.

Paleogeographic Reconstructions

Use fossil evidence, rock formations, and magnetic signatures to reconstruct past continental configurations.

Edicarian Fauna

Early, soft-bodied multicellular organisms that lived around 635 to 541 million years ago.

First Two Supercontinents

Rodinia formed around 1.3 billion years ago, and Pangaea around 335 million years ago.