The Precambrian is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, named after Cambria, the Latinised name for Wales, where rocks from this age were first studied; the Precambrian accounts for 88% of the Earth's geologic time. The Precambrian is an informal unit of geologic time, subdivided into three eons of the geologic time scale, it spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, when hard-shelled creatures first appeared in abundance. Little is known about the Precambrian, despite it making up seven-eighths of the Earth's history, what is known has been discovered from the 1960s onwards; the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, fossils from the Precambrian are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion, or remain buried beneath Phanerozoic strata.
It is thought that the Earth coalesced from material in orbit around the Sun at 4,543 Ma, may have been struck by a large planetesimal shortly after it formed, splitting off material that formed the Moon. A stable crust was in place by 4,433 Ma, since zircon crystals from Western Australia have been dated at 4,404 ± 8 Ma; the term "Precambrian" is recognized by the International Commission on Stratigraphy as the only "supereon" in geologic time. "Precambrian" is still used by geologists and paleontologists for general discussions not requiring the more specific eon names. As of 2010, the United States Geological Survey considers the term informal, lacking a stratigraphic rank. A specific date for the origin of life has not been determined. Carbon found in 3.8 billion-year-old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have been found in Western Australia. Probable fossils 100 million years older have been found in the same area.
However, there is evidence. There is a solid record of bacterial life throughout the remainder of the Precambrian. Excluding a few contested reports of much older forms from North America and India, the first complex multicellular life forms seem to have appeared at 1500 Ma, in the Mesoproterozoic era of the Proterozoic eon. Fossil evidence from the Ediacaran period of such complex life comes from the Lantian formation, at least 580 million years ago. A diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma; these are referred to as Vendian biota. Hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic eon. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale, including some which may represent stem groups of modern taxa; the increase in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life. While land seems to have been devoid of plants and animals and other microbes formed prokaryotic mats that covered terrestrial areas.
Tracks from an animal with leg like appendages have been found in what was mud 551 million years ago. Evidence of the details of plate motions and other tectonic activity in the Precambrian has been poorly preserved, it is believed that small proto-continents existed prior to 4280 Ma, that most of the Earth's landmasses collected into a single supercontinent around 1130 Ma. The supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch 2400–2100 Ma. One of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a "Snowball Earth"; the atmosphere of the early Earth is not well understood. Most geologists believe it was composed of nitrogen, carbon dioxide, other inert gases, was lacking in free oxygen. There is, evidence that an oxygen-rich atmosphere existed since the early Archean. At present, it is still believed that molecular oxygen was not a significant fraction of Earth's atmosphere until after photosynthetic life forms evolved and began to produce it in large quantities as a byproduct of their metabolism.
This radical shift from a chemically inert to an oxidizing atmosphere caused an ecological crisis, sometimes called the oxygen catastrophe. At first, oxygen would have combined with other elements in Earth's crust iron, removing it from the atmosphere. After the supply of oxidizable surfaces ran out, oxygen would have begun to accumulate in the atmosphere, the modern high-oxygen atmosphere would have developed. Evidence for this lies in older rocks that contain massive banded iron formations that were laid down as iron oxides. A terminology has evolved covering the early years of the Earth's existence, as radiometric dating has allowed real dates to be assigned to specific formations and features; the Precambrian is divided into
Hammersmith was a railway station on the London and South Western Railway, located on Grove Road in Hammersmith, west London. It was opened in 1869 and closed in 1916. For much of its existence, the station was served by the Metropolitan Railway and the Great Western Railway, its site was adjacent to another station named Hammersmith, which today is served by the Circle and Hammersmith & City lines. LSWR trains serving Hammersmith ran from Waterloo via Addison Road to Richmond. MR and GWR trains ran from Paddington via the Hammersmith & City Railway and on to Richmond. Hammersmith, as it was named but referred to as Hammersmith, was opened on 1 January 1869 by the LSWR on a new branch line from a junction with the West London Joint Railway north of Addison Road to Richmond via Turnham Green. To the north of Hammersmith the line ran parallel with the HCR before passing under the line and turning through a wide arc south of Shepherd's Bush before reaching the WLJR at a southward pointing junction.
To the west of the station, the line became what is now the District line to Richmond, starting just to the east of Ravenscourt Park. In 1870, Grove Junction was built north of the station connecting the HCR and LSWR tracks, enabling GWR trains on the HCR to access Hammersmith and run on to Richmond. However, the GWR service ran for only a few months during 1870. In June 1877, the District Railway opened an extension from its own Hammersmith station to a junction to connect to the LSWR tracks east of Ravenscourt Park. From 1 October 1877, the MR began to run trains through Hammersmith to Richmond. From 1 January 1894, the GWR initiated services along this route; the more direct route of the DR into central London had a competitive advantage over the other operators of the Richmond service and the other railway companies ended their operations on the Richmond branch. MR services ended on 31 December 1906, shortly after the HCR tracks from Paddington were electrified. GWR services continued until 31 December 1910 and LSWR services continued until 3 June 1916 when the loop line between the Studland Road Junction and Addison Road was closed.
The section west of the junction remains part of the District line. In 1919 the Central London Railway published plans to build a tunnelled link from west of its Shepherd's Bush station to the disused tracks north of the station so that it might run trains to Richmond via Hammersmith and Turnham Green. Although authorisation was granted in 1920, the connection was never realised. Hammersmith was demolished and the loop line to the WLJR was removed, although remnants of the viaduct at the Studland Road Junction where the LSWR tracks turned north-east are still visible west of the current Hammersmith station on the District and Piccadilly lines; the station site is now occupied by an office block on Hammersmith Grove
English singer Harry Styles has released two studio albums, one video album, seven singles, four music videos, one promotional singles. On 7 April 2017, Styles released his first solo single titled "Sign of the Times", reaching number one on the UK Singles Chart, his self-titled debut album was released on 12 May 2017, whereupon it debuted at number one in several countries, including the UK, the US and Australia. On 11 October 2019, Harry Styles released his comeback single "Lights Up" from the then-upcoming album Fine Line; the song debuted at number seventeen on Billboard Hot 100 and at number three on the UK Singles Charts. On November and December 2019, "Watermelon Sugar" and "Adore You" were released as the second and third single from the Styles' second album and peaked at numbers seventeen and seven on the UK Singles Charts, respectively. Fine Line was released on 13 December 2019, debuting at number one on Billboard 200, marking Styles' second number one in the United States after his self-titled debut album, the first British male artist to debut at number one with first two albums.
List of songs written by Harry Styles One Direction discography Notes References