The earlier of the two divisions of the Precambrian Eon, from about 3.8 to 2.5 billion years ago. During this time the Earth had a reducing atmosphere consisting primarily of methane, ammonia, and other gases that would be toxic to most modern life forms. There was little free oxygen. Rocks from the earliest part of the Archean are predominantly volcanic and are similar to pillow basalts, suggesting that they formed underwater. Rocks from the later part of the Archean appear to have formed on continents. It is believed that about 70% of the continental masses formed during this time. Fossils preserved in rocks from this period of time include remains of cyanobacteria, the first single-celled forms of life. These organisms are preserved in the form of stromatolites and oncolites.
The fourth period of the Paleozoic Era, from about 408 to 360 million years ago. During this time there were three major landmasses: most of modern day North America and Europe were located along the equator; a portion of Siberia was located to the north; and a continent consisting of South America, Australia, Africa, India, and Antarctica was located in the Southern Hemisphere. In the early Devonian small plants dominated the landscape, but by the end of the Devonian ferns and seed plants had appeared, as had the first forests. The first tetrapods (terrestrial vertebrates) and terrestrial arthropods appeared, as did many new types of fish.
Designating or of the middle geologic era of the Phanerozoic Eon, subdivided into the Triassic, Jurassic, and Cretaceous periods and characterized by the development and extinction of the dinosaurs and the development of the first birds, mammals, and flowering plants
Of, relating to, or being the epoch of geologic time from about 1.8 million to 10,000 years ago, the older of the two epochs of the Quaternary Period. It is characterized by the alternate appearance and recession of northern glaciation, the appearance and worldwide spread of hominins, and the extinction of numerous land mammals, such as the mammoths, mastodons, and saber-toothed tigers.
Designating or of the second geologic epoch of the Neogene, characterized by the joining of what are now North and South America, the formation of the Arctic ice cap, the extensive migration of mammals between continents, and the development of apelike humans in Africa
The period of geologic time between Hadean Time and the Phanerozoic Eon, from about 3.8 billion to 540 million years ago. During the Precambrian Eon, which is divided into the Archean and Proterozoic, primitive forms of life first appeared on Earth.
Designating or of the first geologic period of the Mesozoic Era, characterized by the breakup of Pangea, the development of tall forests of cycads and conifers, and the presence of the first dinosaurs, turtles, frogs, and small mammals
The earliest epoch of the Tertiary Period, from about 65 to 58 million years ago. During this time, the Rocky Mountains formed and sea levels dropped, exposing dry land in North America, Australia, and Africa. Many new types of small mammals evolved and filled the niches left empty after the extinctions that ended the Cretaceous Period. Soft-bodied squid replaced the ammonites as the dominant form of mollusk.
The final step in the purchase of real property or of an interest in real property when a deed or another instrument of title is conveyed to the buyer, the purchase price or a portion thereof is paid, and collateral matters, such as the exchange or transfer of any assignments, insurance policies, leases, and mortgages, are finalized.
(Baseball) The series of movements of a pitcher, including the swinging back of the arm and the raising of the forward foot, preparatory to pitching the ball. A wind-up is usually used when there are no base runners or when the bases are loaded.
The point, edge, or line beyond which something ends, may not go, or is not allowed:
refers to an indefinitely long period it all happened eons ago
is applied to a period identified with some dominant personality or distinctive characteristic the Stone Age
are often used interchangeably to refer to a period marked by radical change, noteworthy developments, etc. an era, or epoch, of great discoveries, but epoch may specifically apply to the beginning of such a new period the steam engine marked an epoch in transportation, while era applies only to the entire period
is the general term for any portion of time
Find another word for period. In this page you can discover 107 synonyms, antonyms, idiomatic expressions, and related words for period, like: era, full-stop, periodical, recurrent, rhythmical, gestation, etesian, century, close, conclusion and cycle.