Earth Materials and Plate Tectonics Practise Flashcards

This set of vocabulary flashcards covers Earth materials, geologic time scales, rock types, and the principles of plate tectonics as described in the GE02106 lecture.

Age of the Earth

The best estimate for the age of the Earth is $4.54\,Ga$.

Radiometric dating

The technique geologists use to determine the age of rocks by measuring the time since the last melting or reset.

Mesozoic Era

The era of middle life that was dominated by the dinosaurs.

Paleozoic Era

A geologic era referred to as ancient time.

Cenozoic Era

The most recent geologic era, during which nearly all landscape features visible today were formed.

Precambrian time

A period where life has early beginnings but remains absent from the geologic record.

Cambrian Period

The period in geologic time when life on Earth became abundant.

Jack Hills

A location in Western Australia holding the world's oldest rocks found thus far, dating from $4.3$ billion years ago.

Zircon crystals

Tiny crystals examined by geophysicists to determine the ratio of uranium-$238$ to lead-$206$ atoms for dating.

Endogenic processes

Internal volcanic and tectonic activity that brings fresh rocks to the Earth’s surface.

Exogenic processes

External forces such as weathering by wind and water that work the Earth’s surface.

Lithosphere

The solid, brittle outermost layer of the Earth, including the crust and the cooler upper mantle.

Asthenosphere

The plastic layer of the Earth that lies below the lithosphere.

Most abundant element in Earth's crust

Oxygen, which makes up $47\%$ of the crust.

Minerals

Naturally occurring inorganic substances, often possessing a crystalline structure.

Rocks

Substances usually composed of two or more minerals.

Intrusive igneous rocks

Rocks that cool slowly below the Earth's surface and develop visible mineral crystals.

Extrusive igneous rocks

Rocks that cool rapidly on the land surface or ocean bottom, showing microscopic crystals.

Felsic minerals

Minerals that are light-colored and less dense.

Mafic minerals

Minerals that are dark-colored and more dense.

Clastic sedimentary rocks

Rocks formed when rock or mineral fragments are compressed and cemented, such as sandstone and shale.

Metamorphic rocks

Rocks formed from preexisting rocks by intense heat and pressure which alter rock structure and chemical composition.

Topography

The distribution of the Earth's crust into its major surface features.

Alpine chains

Active belts of mountain making built by volcanism and tectonic activity.

Continental shields

Low-lying, inactive regions of old igneous and metamorphic rock eroded to levels of low relief.

Pangaea

A single supercontinent proposed by Alfred Wegener that existed around $250$ million years ago.

Spreading boundary

A plate boundary where the crust is being pulled apart.

Converging boundary

A plate boundary where one plate is subducted beneath another.

Transform boundary

A plate boundary where two plates glide adjacent to each other.

Accretionary wedge

A pile of sea-floor sediment that builds up at a subduction boundary where oceanic lithosphere plates collide.

Continental suture

The junction where two continental lithospheric plates become joined after colliding in an orogeny.

Wilson Cycle

A cycle describing how ocean basins open and close and how continents are split and reunited.

Radiogenic heat

Energy produced when unstable isotopes spontaneously emit energy through radioactive decay and it is absorbed by surrounding matter.