BC or Before Common Era Timeline
- c. 520 BC. ...
- Central Asia. – Alexander the Great conquers Bactria, Margiana, Sogdiana, and Ferghana in a multi-year campaign.
- 305 BC
- Afghanistan. – The Seleucids and Mauryans sign a treaty, which gives control over Arachosia & Gedrosia (most of modern Afghanistan & Pakistan) to the Mauryans.
- Central Asia. ...
- Parthia. ...
- Bactria. ...
- 209 BC
- Parthia. ...
- 206 BC
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4 days ago · This article is part of a series on the History of the United States Timeline and periods Prehistoric and Pre-colonial until 1607 Colonial period 1607–1765 1776–1789 American Revolution 1765–1783 Confederation Period 1783–1788 1789–1849 Federalist Era 1788–1801 Jeffersonian Era 1801–1817 Era of Good Feelings 1817–1825 Jacksonian Era 1825–1849 1849–1865 Civil War Era 1850 ...
4 days ago · From Wikipedia, the free encyclopedia. The history of slavery spans many cultures, nationalities, and religions from ancient times to the present day. Likewise, its victims have come from many different ethnicities and religious groups. The social, economic, and legal positions of slaves have differed vastly in different systems of slavery in ...
- Cenozoic Era
- Mid to Late Mesozoic Era
- Late Palaeozoic to Early Mesozoic Eras
- Early Palaeozoic Era
- Additional References
In the Palaeogene Period, Britain had a very warm climate, but it gradually cooled as Britain drifted northwards. By the Quaternary, glaciers covered the middle and north of Britain, shaping the landscape we see today. The first humans occupied Britain during the Quaternary.
In the Early Cretaceous, Britain experienced a warm climate with lagoonal, lake and fluvial environments. Rocks of this age contain dinosaur remains. Higher sea levels led to chalk deposition in the Late Cretaceous. Many groups of animals became extinct at the end of the Cretaceous, including ammonites and dinosaurs.
In the Jurassic Period, parts of Britain were covered by shallow tropical seas in which mudstones, limestones and sandstones were deposited. The abundant life in the Jurassic included ammonites and dinosaurs.
During the Triassic Period, a hot and dry environment led to the deposition of sandstones, salts and mudstones in deserts, rivers and shallow lakes. Reptiles were common and the first dinosaurs evolved.
During the Permian Period, Britain lay on the supercontinent of Pangaea and experienced hot, dry conditions. Sandstones formed from desert sand dunes. Limestones and salts were deposited in a nearby inland sea (the Zechstein Sea). Many groups of animals became extinct at the end of the Permian.
In the early Carboniferous Period, Britain lay near the equator. Limestones containing corals, brachiopods and trilobites were deposited in shallow seas. Later, sandstones, mudstones and coals were deposited in coastal swamps dominated by forests of giant ferns and horsetails.
In the Devonian Period, Britain lay south of the equator and had a semi-arid climate. Marine limestones, sandstone and mudstones were developed in the south-west. Elsewhere sandstones were deposited by rivers on the coastal plain (sometimes known as the ‘Old Red Sandstone’). Fossils include fish and the first higher plants.
In the Silurian Period, Britain lay south of the equator with a tropical to subtropical climate. A sea covered Britain that was shallower in the south (limestones) and deeper in the north (sandstones and mudstones). Silurian fossils include corals, brachiopods, trilobites and graptolites.
In the Ordovician Period, Britain lay south of the equator and had a cool climate. Seas covered Britain and there was dramatic volcanic activity as the ocean separating England and Wales from Scotland started to close.
In the Cambrian Period, England and Wales lay near the south pole and experienced a cold climate. They were separate from Scotland, which was joined to North America. A shallow sea covered much of the area and animals such as trilobites, graptolites and molluscs first appeared.
The Precambrian is the name given to the span of time prior to the Cambrian. The Precambrian period accounts for 88 per cent of geological time. There are very varied deposits from the Neoproterozoic, including volcanic sequences, sedimentary rocks formed in environments from deep water to terrestrial, plutonic igneous rocks and metamorphic rocks. Multicellular life developed and diversified rapidly. In the Mesoproterozoic Era, England and Scotland lay on different continents. Mudstones, sandstones and volcanic sediments were deposited in shallow seas. Multicellular life developed. The Palaeoproterozoic and Archaean cover a very long period of geological time during which the Earth’s crust and atmosphere were developing. The only life on Earth was single celled.
Several geological timescales exist, reflecting the use of differing datasets and methods of interpretation. The BGS Geological Timechart is based on The Geologic Time Scale 2012(Gradstein et el., 2012), with additions. The result is a composite geological timechart that will be updated as improved timescales become available.
Cowie, J W, and Bassett, M G. 1989. International Union of Geological Sciences 1989 Global Stratigraphic Chart with geochronometric and magnetostratigraphic calibration. Supplement to Episodes, Vol. 12, No. 2. Fortey, R A, Harper, D A T, Ingham, J K, Owen, A W, and Rushton, A W A. 1995. A revision of Ordovician series and stages from the historical type area. Geological Magazine, Vol. 132, 15–30. Gradstein, F M, and Ogg, J. 1996. A Phanerozoic time scale. Episodes, Vol. 19, 3–5.
4 days ago · The Japanese era name (Japanese: 年号, Hepburn: nengō, "year name"), also known as gengō (元号), is the first of the two elements that identify years in the Japanese era calendar scheme. The second element is a number which indicates the year number within the era (with the first year being "gan ( 元 ) "), followed by the literal "nen ...
- 14,000-1000 BC
- 1000 BC-300 AD
6 days ago · The most common dating of the Reformation begins in 1517, when Luther published The Ninety-Five Theses, and concludes in 1648 with the Treaty of Westphalia that ended years of European religious wars. During this period corruption in the Catholic Church led to a sharp backlash in the Protestant Reformation.
- 37.3 (1876)
- 42.7 (1875)
- 36.9 (1876)
- 71.8 (1870)
4 days ago · The history of West Africa has been commonly divided into its prehistory, the Iron Age in Africa, the major polities flourishing, the colonial period, and finally the post-independence era, in which the current nations were formed. West Africa is west of an imagined north-south axis lying close to 10° east longitude, bordered by the Atlantic ...
Jul 21, 2021 · Timeline: Mental illness and war through history. Doctors used to call it "shell shock," "soldier's heart," or "nostalgia." Soldiers would shake uncontrollably, experience heart palpitations, or go blind after witnessing trauma on the battlefield. From as far back as ancient Greece, history reveals the psychological toll of war on soldiers.
- The Animal
- The Geologists’ Tool
- Myths and Legends
- 3D Fossil Models
An array of branching arms (brachia) is arranged around the top of a globe-shaped, cup-like structure (calyx) containing the main body of the animal. In many fossil forms, the calyx was attached to a flexible stem that was anchored to the sea bed. The skeleton is made of the mineral calcite and consists of hundreds of individual plates of different shapes and sizes. Decay of the soft tissue that held many of these plates together means that complete specimens are rare, but parts of the stem are common fossils.
Fossil crinoids indicate that the rocks containing their remains were formed in a marine environment and, where abundant in Palaeozoic rocks, they suggest the former existence of shallow water conditions. In the early Carboniferous, their rich remains (particularly stem fragments) were solidified into rock called crinoidal limestone. Rare occurrences of complete fossilised crinoids indicate rapid burial in quiet, possibly poorly oxygenated waters. Occasionally, crinoids can be a useful guide to the age of the rocks in which they occur. This is the case in the strata the late Cretaceous the Chalk Group, which form the famous White Cliffs of Dover. Species of Uintacrinus, Marsupites, and Applinocrinusare so abundant over four narrow intervals in the Chalk that they have been used to define biozones and subbiozones.
Crinoids are sometimes referred to as sea lillies because of their resemblance to a plant or flower. In parts of England, the columnals forming the stem are called fairy money. Star-shaped examples of these were associated with the sun by ancient peoples and given religious significance. Robert Plot (1640—1696) named these ‘stellate’ forms star stones. Polished slabs of crinoidal limestone make attractive ornamental stone. In Derbyshire, the limestone sometimes contains internal moulds of crinoid stem fragments, which have a distinctive screw-like thread pattern and have been called screwstones. The columnals forming the stem can sometimes be threaded into a necklace and the name St Cuthbert’s beads refers to the saint associated with the legend of making them into rosaries.
Many of the fossils in the BGS palaeontology collections are available to view and download as 3D models. To view this fossil, or others like it, in 3D visit GB3D Type Fossils.