# Geochronology/Dates

Dates are often the day of the month or year as specified by a number, including a particular day or year when a given event occurred or will occur. Sometimes they are the period of time to which an artifact or structure belongs. Then, there is a written, printed, or stamped statement on an item giving the day, month, and year of writing, publication, or manufacture.

## Notations

Conventional dates may appear as
Notation: let April 27, 2016 by denoted as dd month year, or 27 April 2016.
Notation: let dd/mm/yy represent 27 April 2016 as 27/04/16.
Notation: let b2k represent years before J 2000.0.
Notation: let Mya represent millions of years ago, or millions of years b2k.

## Theoretical dates

Def. a "point in [of] time" "at which a transaction or event takes place" is called a date.
Def. a "length of time" "seen as a single coherent entity" the "minimum interval during which the same characteristics [...] recur" is called a period.

## 21st Century

Here on the Earth's surface the ν$_e$ flux is about 10$^{11}$ ν$_e$ cm$^{-2}$ s$^{-1}$ in the direction of the Sun.
"The total number of neutrinos of all types agrees with the number predicted by the computer model of the Sun. Electron neutrinos constitute about a third of the total number of neutrinos. [...] The missing neutrinos were actually present, but in the form of the more difficult to detect muon and tau neutrinos."

## 20th Century

Manned spaceflight on an individual basis has only been achieved with experimental aircraft such as the X-15.

## 19th Century

"This blanket [in the image on the right] was woven at the end of the "wearing blanket era," just as the railroad came into the Southwest in 1881. The heavier handspun yarns and synthetic dyes are typical of pieces made during the transition from blanket weaving to rug weaving."-Ann Hedlund, Arizona State Museum.
The Covered Bridge on the right was built in 1867 near the town of Cedarburg, Wisconsin.
The painting Napoleon I on his Imperial Throne dates to 1806 by artist Jean-Auguste-Dominique Ingres.
Charred material from the Lake Pátzcuaro Basin, Mexico, was radiocarbon dated at 1715-1895 AD (120 b2k intercept).

## 18th Century

The more recent dated logboat of Ireland is from or known as Bond's Bridge, Cos AmlaghJTyrone, to 245 ± 15 b2k.
Taken from the observation platform at the top of the Jantar Mantar, the image on the right shows smaller architectural sundials. The Jantar Mantar is a collection of architectural astronomical instruments, built by Maharaja Jai Singh II at his then new capital of Jaipur between 1727 and 1733. The City Palace is behind then Govindji Temple. Nahargarh Fort is on the Hill.

## 17th Century

The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s (the 17th century), using glass lenses.
The Keplerian Telescope was invented by Johannes Kepler in 1611.
"The central piece of information uncovered by de Waard was an entry in the unpublished journal of Isaac Beeckman, the rector of the Latin school in Dordrecht, and a friend of Descartes.$^{37}$ Beeckman learned how to grind lenses for telescopes in an effort to obtain better instruments. In the early 1630's he took lessons from a spectacle-maker in Middelburg named Johannes Sachariassen, the son of Sacharias Janssen. Beeckman recorded in his journal that during one of these lessons Johannes Sachariassen told him that the first telescope in the Netherlands had been made in 1604 by his father, after the model of an instrument in the possession of an Italian. This instrument bore the date of 1590.$^{38}$"

## 16th Century

A logboat from Ireland (Derryloughan B, Co. Tyrone) designated GrN-14738 dates to 410 ± 35 b2k.
As many Italians were in the Netherlands fighting the Spanish, some with experience in grinding lenses for optical uses, it is likely a few carried with them optical transits such as the one dated to 1590 made in Italy which were so common as to be taken for granted by historians, modifiable into telescopes.
The image on the top right shows the sphere without sighting tubes or any device for observing astronomical objects and dates from 1547.
Angamuco "occupied 26 square kilometers of land instead of 13 square kilometers."
"That is a huge area [second image down on the right] with a lot of people and a lot of architectural foundations that are represented."
"If you do the maths, all of a sudden you are talking about 40,000 building foundations up there, which is [about] the same number of building foundations that are on the island of Manhattan."
Angamuco "had an unusual layout, with big structures like pyramids and open plazas situated around the edges rather than in the center."
"The Purépecha people existed at the same time as the Aztecs. While they are nowhere near as popular as their rivals, they were still a major civilization and had an imperial capital called Tzintzuntzan in western Mexico. Based on [...] LiDAR scans, though, Angamuco is even bigger Tzintzuntzan. It likely wasn't as densely populated, but [...] it's now the biggest city in western Mexico during that period that we know of."
"In I523 Cortes quietly appropriated for himself the great Tarascan-held silver district of Tamazula (Jalisco)."

## 15th Century

The image at the right dating from c. 1480 shows the sphere without sighting tube or any device for observing astronomical objects.
"Italy from the peace of Lodi to the first French invasion (1454-94): the era of equilibrium" is near the end of the late Middle Ages.
A logboat from Ireland, Derryloughan A, Co. Tyrone, designated GrN-14737, has been radiocarbon dated to 570 ± 25 BP or b2k.
On the right is an image of an incense burner from the Tarascan culture, showing a deity with a "Tlaloc headdress", 1350 - 1521 AD, from the Snite Museum of Art.
The image second down on the right hangs in the interior of the ayuntamiento of San Cristobal de La Laguna, Tenerife.
The painting on the right shows the surrender of the Guanches kings of Tenerife to Ferdinand and Isabella. This appears to have occurred c. 504 b2k.
The painting on the left was painted in 1764. It depicts the surrender of the Guanches leaders Bencomo mencey with Tacoronte, Anaga and Tegueste to Governor Alonso Fernández de Lugo with his captains and noble friends, by bringing gifts to the governor.

## 14th Century

The remains of a pre-Hispanic temazcal in the image on the right recently found in Mexico City helped archaeologists pinpoint the location of the ancient neighborhood of Temazcaltitlan.
"Mexico City stands on the ancient site of Tenochtitlán, which, by the late 15th century, had emerged as the bustling capital of the Aztec Empire. One of the city’s oldest neighborhoods was Temazcaltitlan, known as a spiritual hub for the worship of female deities."
The "temazcal, as steam baths are called in the indigenous Nahuatl language, was found near Mexico City’s modern La Merced neighborhood. It is a domed structure, spanning about 16.5 feet long by 10 feet wide, and was made from adobe blocks and stucco-coated tezontle, a type of volcanic rock."
"[Y]ou can see the tub or water pool for the steam bath, as well as one of the sidewalks that were part of it."
"The area was known for at least one temazcal, mentioned in the Crónica Mexicáyotl by Hernando Alvarado Tezozómoc, a 16th-century Nahua nobleman who wrote about the ascendance and fall of the Aztec capital. According to Tezozómoc, a temazcal was built in the area to purify a noble girl named Quetzalmoyahuatzin; the neighborhood got its name, Tezozómoc notes, because “all the Mexicans bathed […] there.”"
"Temazcaltitlan was associated with the worship of female deities of fertility, water, and pulque, a fermented agave drink with ancient roots; the Aztec goddess Mayahuel is often depicted with agave sap pouring from her breasts. The discovery of the temazcal, experts say, confirms the neighborhood’s status as a spiritual center."
The image at the left shows a sceptre dated to before 1380.

## 13th Century

The ruin tower on the right is apparently dated to the 13th Century and was built by the Anasazi.
Italian humanism began in the first century of the late Middle Ages (c.1350-1450).
"The processed image at the right [in the images on the right] is the product of the application of digital filters. Digital filters are mathematical functions that do not add any information to the image, but transform it in such a way that information already present in it becomes more visible or easier to appreciate by the naked eye. The processed image was produced by inverting the brightness of the pixels in the positive image but without inverting their hue, and then by increasing both the brightness contrast and the hue saturation. Finally noise and so-called “salt and pepper” filters automatically removed the noisy information from the original image which hinders the appreciation of the actual face. To my knowledge the resulting image is the best available and indeed the only one that reveals the color information hidden in the original."
Radiocarbon dating of a corner piece of the shroud placed it between the years 1260 and 1390, in the High to Late Middle Ages, which is consistent with "its first recorded exhibition in France in 1357."
The book was bound more than 100 years later with covers made of oak surrounded by leather, where the oak has been dated to 1264 using dendrochronology, and the oak trees used grew in the vicinity of Skara.
"In a meta-analysis of 1,434 radiocarbon dates from the region, reliable short-lived samples reveal that the colonization of East Polynesia occurred in two distinct phases: earliest in the Society Islands A.D. ~1025–1120, four centuries later than previously assumed; then after 70–265 y, dispersal continued in one major pulse to all remaining islands [15 archipelagos of East Polynesia, including New Zealand, Hawaii, and Rapa Nui] A.D. ∼1190–1290."
"The town of Tzintzuntzan, in addition to being a Pueblo Magico, is the heartland of Michoacan’s indigenous culture as it once served as the ceremonial center and capital of the Purépecha empire (Tarascan). The ceremonial center now is an outstanding archaeological site that contains five temples, called yacatas, which date back to the 13th century. Tzintzuntzan’s indigenous customs, traditions, and language are still very much present today."

## 12th Century

Romanesque apses and brick towers of the Church of San Tirso, Sahagún, are shown on the right, dated to the 12th Century.
Recent dating of Sweden's oldest book, the Skara Missal [in the image on the left] shows that the book is just that: Sweden's oldest.
Researchers at Lund University concluded using radiocarbon dating that the book's pages are from the year 1150, i.e. at the time of the opening of the Skara cathedral.

## 11th Century

The star map on the right, which features a cylindrical projection, was published in 1092 and has a corrected position for the pole star using Shen Kuo's astronomical observations.
"All 5 pieces of the famous Swedish Överhogdal [tapestries such as the portion shown in the image on the right] were examined [by radiocarbon dating to 900 - 1100]."
Radiocarbon dating of charcoal fragments from Koumbi Salehin, a settlement in south east Mauritania, indicate the site was continuously occupied from the 8th/9th to the 13th centuries.

## 10th Century

Visby was founded in the 10th century, on the then independent Baltic Sea island of Gotland. The Hansaetic League formed it during ensuing centuries, during which it came to Denmark. In 1645, it came into Swedish occupation, in which it has remained until today.
There is more about lenses more recently from Visby, Gotland.
"What intrigues the researchers is that the lenses are of such high quality that they could have been used to make a telescope some 500 years before the first known crude telescopes were constructed in Europe in the last few years of the 16th century."
"Made from rock-crystal, the lenses have an accurate shape that betrays the work of a master craftsman. The best example of the lenses measures 50 mm (2 inches) in diameter and 30 mm (1 inch) thick at its centre."
"The [Visby] Gotland crystals provide the first evidence that sophisticated lens-making techniques were being used by craftsmen over a 1,000 years ago."

## 9th Century

There was an inscription which placed the foundation of the nilometer in 861.
Cobá is a former pre-Columbian Mayan city on the Yucatán Peninsula southeast of Valladolid located in the state of Quintana Roo, Mexico.
In Cobá, the temple pyramid Nohoch-Mul (also known as Castillo, or the climbing pyramid shown on the left) is 42 meters high.
The city was founded shortly after the beginning of the year and expanded into a city state that peaked between 600 and 800 (1400 and 1200 b2k).

## 8th Century

The Dunhuang map from the Tang Dynasty of the North Polar region at right is thought to date from the reign of Emperor Zhongzong of Tang (705–710). Constellations of the three schools are distinguished with different colors: white, black and yellow for stars of Wu Xian, Gan De and Shi Shen respectively. The whole set of star maps contains 1,300 stars.
The Dunhuang Star Atlas, the last section of manuscript Or.8210/S.3326. It is "the oldest manuscript star atlas known today from any civilisation, probably dating from around AD 700. It shows a complete representation of the Chinese sky in 13 charts with over 1300 stars named and accurately presented."
"The Dunhuang Star Atlas [above center] forms the second part of a longer scroll (Or.8210/S.3326) that measures 210 cm long by 24.4 cm wide and is made of fine paper in thirteen separate panels."
"The first part of the scroll is a manual for divination based on the shape of clouds. The twelve charts showing different sections of the sky follow these. The stars are named and there is also explanatory text. The final chart is of the north-polar region. The chart is detailed, showing a total of 1345 stars in 257 clearly marked and named asterisms, or constellations, including all twenty-eight mansions."
"The importance of the chart lies in both its accuracy and graphic quality. The chart includes both bright and faint stars, visible to the naked eye from north central China".

## 7th Century

Sambor Pre Kuk, with its N16 Sanctuary imaged on the right, is an archaeological complex formed by the remains of the city of Isanapura, the capital of the kingdom of Chenla, an immediate predecessor of the Khmer Empire (pre-Angkorian).
This city was built during the reign of Isanavarman I (616-635). At this time, several constructions, clear predecessors of Khmer architecture, were erected in Angkor.
Cantona is a Mesoamerican archaeological site in the state of Puebla, Mexico. It was a fortified city with a high urbanization level at prehispanic times, probably founded by Olmec-Xicalanca groups towards the late Classical Period. It sat astride an old trading route between the Gulf Coast and the Central Highlands and was a prominent, if isolated, Mesoamerican city between 600 and 1000 CE. After Chichimec's invasions in the 11th century, Cantona was abandoned.
Cantona's inhabitants were mainly agricultural farmers and traders, particularly for obsidian, obtained from Oyameles-Zaragoza mountains surrounding the city. Additionally, they may have been supplying the lowlands with a derivative of the maguey plant, pulque. Cantona's population is estimated at about 80,000 inhabitants at its peak.
Cantona may well be the largest prehispanic city yet discovered in Mesoamerica. Limited archaeological work has been done at the site, and only about 10% of the site can be seen. The Pre-Columbian settlement area occupies approximately 12 km², distributed in three units, of which the largest is at the south, with a surface of 5 km². The site comprises a road network with over 500 cobblestone causeways, more than 3,000 individual patios, residences, and 24 ball courts - more than in any other mesoamerican site. It has an elevated Acropolis over the rest of the city in which the main buildings of the city were built. This was used for the ruling elite and priests, and was where the temples of the most important deities where located. These impressive buildings were constructed with carved stones (one atop the other) without any stucco or cement mortar. Cantona certainly was built with a definite urban design and walkways connecting each and every part of the city. The "First Avenue" is 563 meters in length.

## 6th Century

On the right is the Basilica Cistern in Constantinople, Turkey. It has been dated to the 6th century.
Dzibanche is an archaeological site which includes the Temple of the Owl pyramid. It is an ancient Maya site located in southern Quintana Roo, in the Yucatan Peninsula of southeastern Mexico.
Structures at Dzibanche include the Temple of the Captives, the Temple of the Lintels and the Temple of the Owl, on the left.
"AMS [Accelerator mass spectrometry] $^{14}$C dating [summarized on the left] indicates that the age [of Can Ferrerons, a Roman octagonal building in Premià de Mar, Barcelona, with an image of the Tepidarium on the right] is between CE 420–540, at 95.4% confidence level."
A logboat from Ireland West Ward I, Co. Tyrone, designated GrN-16863, has been radiocarbon dated to 1440 ± 30 BP or b2k.

## 5th Century

Ancient India was an early leader in metallurgy, as evidenced by the wrought-iron Pillar of Delhi in the image on the right, dated to about 415 or 1585 b2k.
"The Saxons tended to avoid Roman sites possibly because they used different farming methods."
"[We] learn from Prof. Fleming [2016] that Roman conquerors introduced many — perhaps as many as 50 — new and valuable food plants and animals (such as the donkey) to its province of Britannia, where these crops were successfully cultivated for some 300 years. Among the foodstuffs that Roman civilization brought to Britain are walnuts, carrots, broad beans, grapes, beets, cabbage, leeks, turnips, parsnips, cucumbers, cherries, plums, peaches, almonds, chestnuts, pears, lettuce, celery, white mustard, mint, einkorn, millet, and many more. These valuable plants took root in Britain and so did Roman horticulture. British gardens produced a bounty of tasty and nourishing foods. [...] Following the collapse of Roman rule after 400 AD, almost all of these food plants vanished from Britain, as did Roman horticulture itself. Post-Roman Britons [...] suddenly went from gardening to foraging. Even Roman water mills vanished from British streams. But similar mills came back in large numbers in the 10th and 11th centuries, along with Roman food plants and farming techniques."
"Wat's Dyke has recently been redated to the fifth century. The dyke runs parallel to the eighth-century Offa's Dyke in the Welsh Marches. This area marked the border between the British kingdom of Powys and Mercia in medieval times. Excavations at Maes-y-Clawdd near Oswestry have discovered a site along the dyke that contained the remains of a small fire and Roman-British pottery. The charcoal from the fire had been radiocarbon dated to AD 411-561. It has been suggested that the dyke was associated with the Romano-British kingdom based on the city of Wroxter."
A logboat from Ireland Strabane, Co. Derry, has been dendrodated to 431 AD and radiocarbon dated 1610 BP or b2k.
Another Oxford Island, Co. Amlagh (Kinnegoe), has been dendrodated to 492 AD and radiocarbon dated 1590 BP or b2k.

## 4th Century

The House of Peter in Capernaum, Israel, has been dated to the 4th century.
"Recent archaeological excavations have focused on the late fourth and fifth centuries. The discovery of two young adult skeletons in a burial pit in the courtyard of the commander's house have been dated to the early fifth century. The bodies were not buried immediately after their deaths but were left [...] for animals to prey upon before they were thrown into the burial pit. The bodies of the young man and young woman have been radiocarbon dated to 140-430 AD cal. and 340-660 AD. Archaeologists believe that the commander's house was already in ruins at the time of their deaths, and the burial in the pit suggests the Roman community was no longer present at Arebia. The end of the occupation can be tentatively dated by two coins dated to AD 388-402 found on the floor of the commander's house. These coins are the latest Roman coins to be found anywhere along the northern Roman defenses. This last period of Roman occupation was active, with the fort's garrison and defenses consistently maintained. The fortress was remodeled or repaired in the same period since another coin dating to 388-402 was found in the resurfaced road of the rebuilt west gate. This combined data suggests that the fortress was occupied by the Romans until the end of the fourth century and that the end came rapidly."
A logboat from Ireland, Drummans Lower, Co. Leitrim, designated GrN-18756 has been radiocarbon dated to 1630 ± 30 BP or b2k.

## 3rd Century

In the late imperial antiquity map on the right, provincial boundaries (dashed red lines) are approximate and, in many places, very uncertain.
"Many [British] building sequences appear to terminate in the 2nd and 3rd centuries [1900-1700 b2k]. [...] The latest Roman levels are sealed by deposits of dark coloured loam, commonly called the 'dark earth' (formerly 'black earth'). In the London area the 'dark earth' generally appears as a dark grey, rather silty loam with various inclusions, especially building material. The deposit is usually without stratification and homogeneous in appearance, It can be one meter or more in thickness. [...] The evidence suggests that truncation of late Roman stratification is linked to the process of 'dark earth' formation."
“Parts [of Londinium] / were already covered by a horizon of dark silts (often described as 'dark earth') / Land was converted to arable and pastoral use or abandoned entirely. The dark earth may have started forming in the 3rd century."
A logboat from Britain 168 Wisley designated Q-1399 has been radiocarbon dated to 1780 ± 45 BP or b2k.

## 2nd Century

"[2nd/3rd century AD] Ptolemy’s PHA-BIRABON is identified with Bremen though there are other candidates, too. Rich evidence for Roman period. Settlements of 1st century are continued."
The last known celestial globe shown at the right dates from 1850 to 1780 b2k. The constellation illustrations from the Mainz celestial globe are shown at the left.
"After Octavian/Augustus (31 BCE – 14 CE) had, in 30 BCE, turned Egypt into an imperial province of the Roman Empire, Memphis continued to thrive. Suetonius (69-122) writes about the city in his Life of Titus (part XI of The Twelve Caesars)."
A 2nd-century sculpture on the right perhaps shows Phosphorus (the Morning star) and Hesperus (the Evening star) on either side of the Moon (Selene or Luna).
A logboat from Ireland Crevinish Bay l, Co. Femlanagh, designated HAR-1969, has been radiocarbon dated to 1860 ± 70 BP or b2k.
On the left is an image of the oldest extant diagram of Euclid's Elements, found at Oxyrhynchus and dated to c. 100 AD.

## 1st Century

On the left is a Roman fresca of Venus standing on a quadriga of elephants from the Officina di Verecundus (IX 7, 5) in Pompeii, first century.
"[1st century AD] Saxon Chauci create rich building evidence. 50 m long houses (three aisles) with integrated stables are found all over the city and many suburbs; blacksmith shops; charcoal kiln technology etc."
"A succession of fires allowed the preservation of all the elements in place, when the inhabitants ran away from the catatrophe, transforming the area into a real little Pompei of Vienne [image on the right]."
"The fire brought the top floor, the roof and the terrasse of a sumptuous dwelling to collapse, both caved in floors being preserved, with the furniture left in place. The house, dating from the second half of the first century and surrounded by gardens, was baptised "House of the Bacchae" because of a mosaic with a cortege of bacchae surrounding a Bacchus."
"With many others, a superb mosaic preserved in its near-totality in the "House of Thalia and Pan" has been lifted with much precaution earlier this week, to be restored at the ateliers of the gallo-roman museum of Saint-Romain-en-Gal."
"The Roman city of Vienne, in Southeast France, was at a crossroads of communications, between the Rhône River and the Roman province of Gallia Narbonensis, on a "highway" connecting Lyon, the capital of Gaul, to the city of Arles. Another axis of circulation had most probably preceded it and the excavations «provide also an exceptional opportunity to analyze the anterior states of the Roman road of Gallia Narbonensis, or Transalpine Gaul, "one of the most important of this time.""
"Besides the two luxurious houses, the neighborhood included shops dedicated to metalwork, food stores and other artisanal production; a warehouse full of jugs for wine; and a hydraulic network that allows for cleaning and drainage. The neighborhood appeared to be built around a market square, apparently the largest of its kind to be discovered in France."
A logboat from Britain 7 Baddiley Mere designated Q-1496 has been radiocarbon dated to 1980 ± 50 BP or b2k.
Pompeii lens (plano-convex) from the excavations of the Via Stabia, "House of the Engraver" dated to 79 AD per E. Gerspach, L'art de la verrerie (Paris 1885) 41-42.
Roman London lens (fragmentary biconvex glass lens of light green color), from Roman London, dated to 43-50 AD per H. Syer Cuming, "On Spectacles," The Journal of the British Archaeological Association 11 (1855) 144-49.

## Hypotheses

* The sciences do not need to follow the humanities, religion, or the arts to be beneficial to humanity.
* The scientific method is not a recent occurrence.