Earth Science

Geological era between the Paleozoic and Cenozoic eras, lasting from 252 to 66 million years ago.

Three periods that make up the Mesozoic era, characterized by the rise and fall of different species.

A nickname for the Mesozoic era, highlighting the dominance of reptiles, including dinosaurs.

Geological era before the Mesozoic era, lasting about 300 million years, known as the "age of ancient life."

First period of the Paleozoic Era, marked by the development of protective shells in many organisms.

Geological era following the Mesozoic era, marked by the age of mammals and flowering plants. (current era).

significant extinction event at the end of the Mesozoic era, which wiped out many species, including the non-avian dinosaurs.

Supercontinent that existed during the Mesozoic Era. Started to break apart ~200 million years ago.

Rocks formed from compressed particles like sand, mud, or organic matter.

Younger rocks are found on top of older rocks in undisturbed layers.

Determining the age of something by comparing it to other things.

Techniques used to find the age of materials, including rocks.

Rock layers formed in sequence, one on top of another.

Preserved remains or traces of ancient organisms found in rocks.

Sedimentary rock formed from compressed gravel.

Sedimentary rock formed from compressed sand.

Sedimentary rock formed from compressed mud.

The first eon (4.5-4.0 billion years ago), characterized by intense bombardment from asteroids and meteorites, early oceans, and the beginning of the hydrologic cycle.

Fundamental concepts in stratigraphy (study of rock layers) including superposition, original horizontality, lateral continuity, and cross-cutting relationships.

The eon (4.0-2.5 billion years ago) marked by slowing meteorite impacts, cooling Earth, forming clouds, and hardening the crust. Early life forms were anaerobic (lacking oxygen).

Photosynthetic bacteria (blue-green algae) that emerged during the Archean eon and started releasing oxygen.

An eon (2.5 billion - 541 million years ago) with increasing oxygen levels in the atmosphere (~3%), rise of multicellular organisms (Vendian fauna), and the formation of an ozone layer.

Organisms composed of more than one cell, appearing in the Proterozoic eon.

The current eon, starting about 541 million years ago, marked by visible life forms.

A period within the Phanerozoic Eon characterized by a tropical and humid climate, rapid insect evolution, and the appearance of giant insects.

A period in the Phanerozoic Eon where two groups of reptiles (diapsids and synapsids) were dominant.

Complex single-celled or multicellular organisms with a nucleus and other membrane-bound organelles. They appeared later than prokaryotes.

A flat, deep-sea floor region found far from land, covered in sediment.

An underwater mountain created by volcanic activity.

A flat-topped seamount, often formed by erosion.

A major oceanic ridge in the Pacific Ocean, known for active seafloor spreading.

The cyclical opening and closing of ocean basins caused by plate movement.

States that in undisturbed rock layers, the oldest layers are at the bottom and the youngest at the top.

Groups of fossils found together in a specific rock layer, indicating the types of organisms that lived at that time.

Fossils occur in a specific sequence from oldest to youngest in rock layers.

A method used to determine the age of rocks and fossils by measuring the ratio of radioactive isotopes to their decay products.

The time it takes for half of a radioactive isotope to decay.

The earliest and longest time period in Earth's history, lasting from about 4.5 billion to 541 million years ago.

Another name for the Pre-cambrian Time, meaning 'hidden life' because fossils from this time are scarce.

These are the major divisions of the geologic timescale, from largest to smallest.

Early life forms that used sunlight to produce energy, releasing oxygen as a byproduct.

A layer in the Earth's atmosphere that absorbs harmful ultraviolet radiation from the sun.