Mammals and birds are the dominant vertebrates on land, teleost fish in the sea, and angiosperms (flowering plants) and in certain areas conifers the predominant form of plant life.more Closed system: A system (rock, planet, etc.) which has no influence or exchange with the outside world.In reality there is always some exchange or influence, but if this amount is completely insignificant for the process under consideration (e.g., for dating, if the loss or gain of atoms is insignificant) for practical purposes the system can be considered closed.

geologic dating definition-77geologic dating definition-16geologic dating definition-55

They are stopped by the earth's atmosphere, but in the process, they constantly produce carbon-14, beryllium-10, chlorine-36, and a few other radioactive isotopes in small quantities. Carbon-14 is said to be cosmogenic because it is produced by cosmic rays.

Cross-cutting relationships: Geologic discontinuities that suggest relative ages: A geologic feature is younger than the feature it cuts.

Thus, a fault cutting across a rock is younger than the rock.

An atom may share electrons with an adjacent atom or atoms; the result being a molecule.

( Beta decay: The process of radioactive decay in which a neutron loses a beta particle (i.e. This increases the atomic number of the atom by one by turning the neutron into a proton.

The atom's atomic mass number stays the same because the total number of protons and neutrons remain the same. Carbon-14: See Radiocarbon Cenozoic: "Recent Animal Life".

The third and current (most recent) geologic era of the Phanerozoic Eon, which began 65.5 million years ago; colloquially referred to the "Age of Mammals".

: The following is taken from several on-line sources, chiefly Illustrated Glossary of Geologic Terms by Steven M. Richardson (Englewood Cliffs, NJ, Prentice Hall, 1995); definitions conform generally, and in some cases specifically, to definitions given in Robert L Bates and Julia A Jackson (editors), Glossary of Geology, 3rd ed., American Geological Institute, Alexandria, Virginia, 1987.), and Radiometric Dating A Christian Perspective Dr. Wiens Division of Geological & Planetary Sciences California Institute of Technology reprinted from Graham Kendell archives. Elsberry's talk.origins jargon FAQOriginal definitions by yours truly are initialed thus: " Archean: The second oldest eon in Earth history.

Richardson, professor of geology at Iowa State University (based on the glossary in Earth: An Introduction to Geologic Change, by S. It followed the Hadean, and lasted from around 3.8 to 2.5 billion years ago.

During this time prokaryote life appeared and flourished, and the Earth was characterised by a reducing (anaerobic) atmosphere. More Atom: The smallest unit that has the chemical characteristics of a particular chemical element.

It is about ten billionths of an inch in diameter and is made of a dense central nucleus of protons and neutrons, surrounded by a cloud of electrons.