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20-580: The Zuñi River begins about 4.5 miles east-northeast of Black Rock at the confluence of the Rio Pescado and Rio Nutria . It was dammed at Black Rock in 1908 forming the Black Rock Reservoir. The river has a small dam at the Zuni Pueblo . The river is intermittent, drying up during drought periods, and often during most of the winter, except where there are perennial springs that give it surface flow for

40-572: A short distance. The Zuni Basin is home to the Moreno Hill Formation where fossils from the later Cretaceous 92 Mya. Fossils include dinosaurs like Zuniceratops and Suskityrannus (Zuni Coelurosaur). The Zuni River is one of the last remaining habitats of the Zuni bluehead sucker . The Zuni River is sacred to the Zuni people . Every four years, a religious pilgrimage is made on the "Barefoot Trail" to Kołuwala:wa , also called "Zuni Heaven", at

60-469: Is a time scale used mainly in archaeology , geology, and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because the "present" time changes, standard practice is to use 1 January 1950 as the commencement date (epoch) of the age scale, with 1950 being labelled as the "standard year". The abbreviation "BP" has been interpreted retrospectively as "Before Physics", which refers to

80-567: Is an unincorporated community and census-designated place (CDP) in McKinley County , New Mexico , United States. The population was 1,190 at the 2020 census , down from 1,323 in 2010 . There was a spring at Black Rock and the Zuñi had irrigated fields there since about 3000 BP (950 BCE ). The Zuñi had a small, seasonally occupied village on the lava flow, just north of the Zuni River, which

100-478: Is sometimes used for dates established by means other than radiocarbon dating, such as stratigraphy . This usage differs from the recommendation by van der Plicht & Hogg, followed by the Quaternary Science Reviews , both of which requested that publications should use the unit "a" (for "annum", Latin for "year") and reserve the term "BP" for radiocarbon estimations. Some archaeologists use

120-670: The Little Colorado River , which it joins near Hunt, Arizona . As of the census of 2000, there were 1,252 people, 319 households, and 283 families residing in the CDP. The population density was 740.1 inhabitants per square mile (285.8/km ). There were 349 housing units at an average density of 206.3 per square mile (79.7/km ). The racial makeup of the CDP was 89.70% Native American , 7.99% White , 0.24% from other races , 0.16% African American , 0.16% Asian , and 1.76% from two or more races. Hispanic or Latino of any race were 2.72% of

140-590: The Spanish called "Ranchos de Zuñi". Black Rock is located on the Zuñi Reservation on the left bank (south side) of the Zuñi River , approximately 4 miles (6 km) east of the town of Zuñi , on the north side of NM Route 53 . Immediately to the east of the community is the Black Rock Reservoir, which was created in 1908 by damming the Zuni River. The dam has undergone serious rebuilding three times since 1908,

160-400: The average family size was 4.06. In the CDP, the population was spread out, with 44.3% under the age of 18, 8.1% from 18 to 24, 33.8% from 25 to 44, 10.9% from 45 to 64, and 2.9% who were 65 years of age or older. The median age was 22 years. For every 100 females, there were 87.1 males. For every 100 females age 18 and over, there were 81.0 males. The median income for a household in the CDP

180-1587: The confluence of the Zuni River and the Little Colorado. Download coordinates as: 34°38′46″N 109°37′32″W  /  34.646144°N 109.625664°W  / 34.646144; -109.625664 34°38′59″N 109°30′02″W  /  34.649754°N 109.500663°W  / 34.649754; -109.500663 34°39′42″N 109°22′32″W  /  34.661701°N 109.375656°W  / 34.661701; -109.375656 34°43′47″N 109°15′02″W  /  34.729759°N 109.250650°W  / 34.729759; -109.250650 34°45′00″N 109°13′40″W  /  34.750037°N 109.227872°W  / 34.750037; -109.227872 34°49′48″N 109°07′31″W  /  34.830036°N 109.125369°W  / 34.830036; -109.125369 34°52′30″N 109°02′32″W  /  34.875036°N 109.04231°W  / 34.875036; -109.04231 34°57′37″N 109°00′02″W  /  34.960312°N 109.000641°W  / 34.960312; -109.000641 35°00′00″N 108°59′05″W  /  35.000033°N 108.984807°W  / 35.000033; -108.984807 35°03′30″N 108°52′31″W  /  35.058366°N 108.875362°W  / 35.058366; -108.875362 35°06′38″N 108°42′56″W  /  35.110588°N 108.715637°W  / 35.110588; -108.715637  ( Zuñi River source ) Black Rock, New Mexico Black Rock ( Navajo : Tsézhįįh Deezlį́ )

200-471: The exponential decay relation and the "Libby half-life" 5568 a. The ages are expressed in years before present (BP) where "present" is defined as AD 1950. The year 1950 was chosen because it was the standard astronomical epoch at that time. It also marked the publication of the first radiocarbon dates in December 1949, and 1950 also antedates large-scale atmospheric testing of nuclear weapons , which altered

220-480: The global ratio of carbon-14 to carbon-12 . Dates determined using radiocarbon dating come as two kinds: uncalibrated (also called Libby or raw ) and calibrated (also called Cambridge ) dates. Uncalibrated radiocarbon dates should be clearly noted as such by "uncalibrated years BP", because they are not identical to calendar dates. This has to do with the fact that the level of atmospheric radiocarbon ( carbon-14 or C) has not been strictly constant during

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240-780: The lowercase letters bp , bc and ad as terminology for uncalibrated dates for these eras. The Centre for Ice and Climate at the University of Copenhagen instead uses the unambiguous "b2k", for "years before 2000 AD", often in combination with the Greenland Ice Core Chronology 2005 (GICC05) time scale. Some authors who use the YBP dating format also use "YAP" ("years after present") to denote years after 1950. SI prefix multipliers may be used to express larger periods of time, e.g. ka BP (thousand years BP), Ma BP (million years BP) and many others . Radiocarbon dating

260-543: The most recent in the mid-1990s. Black Rock has a non-commercial airstrip built just after World War II , but not paved until 1970. According to the United States Census Bureau , the Black Rock CDP has a total area of 1.80 square miles (4.7 km ), of which 1.75 square miles (4.5 km ) are land and 0.05 square miles (0.13 km ), or 3.00%, are water. The Zuni River is a west-flowing tributary of

280-508: The name (standard codes are used) of the laboratory concerned, and other information such as confidence levels, because of differences between the methods used by different laboratories and changes in calibrating methods. Conversion from Gregorian calendar years to Before Present years is by starting with the 1950-01-01 epoch of the Gregorian calendar and increasing the BP year count with each year into

300-405: The population. There were 319 households, out of which 62.1% had children under the age of 18 living with them, 45.1% were married couples living together, 35.4% had a female householder with no husband present, and 11.0% were non-families. 9.7% of all households were made up of individuals, and 0.6% had someone living alone who was 65 years of age or older. The average household size was 3.88 and

320-596: The span of time that can be radiocarbon-dated. Uncalibrated radiocarbon ages can be converted to calendar dates by calibration curves based on comparison of raw radiocarbon dates of samples independently dated by other methods, such as dendrochronology (dating based on tree growth-rings) and stratigraphy (dating based on sediment layers in mud or sedimentary rock). Such calibrated dates are expressed as cal BP, where "cal" indicates "calibrated years", or "calendar years", before 1950. Many scholarly and scientific journals require that published calibrated results be accompanied by

340-399: The time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, which scientists must account for. In a convention that is not always observed, many sources restrict the use of BP dates to those produced with radiocarbon dating; the alternative notation "RCYBP" stands for the explicit "radio carbon years before present". The BP scale

360-723: Was $ 16,442, and the median income for a family was $ 14,950. Males had a median income of $ 17,105 versus $ 16,563 for females. The per capita income for the CDP was $ 6,952. About 57.2% of families and 61.8% of the population were below the poverty line , including 73.8% of those under age 18 and 100.0% of those age 65 or over. It is in Zuni Public Schools . Zuni High School is the zoned high school. Tribally-run A:shiwi Transit connects Zuni Pueblo and Black Rock with Gallup . [REDACTED] Media related to Black Rock, New Mexico at Wikimedia Commons Before Present Before Present ( BP ) or " years before present ( YBP )"

380-446: Was first used in 1949. Beginning in 1954, metrologists established 1950 as the origin year for the BP scale for use with radiocarbon dating, using a 1950-based reference sample of oxalic acid . According to scientist A. Currie Lloyd: The problem was tackled by the international radiocarbon community in the late 1950s, in cooperation with the U.S. National Bureau of Standards . A large quantity of contemporary oxalic acid dihydrate

400-525: Was prepared as NBS Standard Reference Material (SRM) 4990B. Its C concentration was about 5% above what was believed to be the natural level, so the standard for radiocarbon dating was defined as 0.95 times the C concentration of this material, adjusted to a C reference value of −19 per mil (PDB). This value is defined as "modern carbon" referenced to AD 1950. Radiocarbon measurements are compared to this modern carbon value, and expressed as "fraction of modern" (fM). "Radiocarbon ages" are calculated from fM using

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