Rock formations found on what is now the eastern slope of the San Gabriel Mountains begin to form beneath an ancient sea. The coastline is found quite a bit east of its present location in what is now Utah and Idaho.
Toward the beginning of the Cenozoic Era, the Los Angeles Basin and area mountains lie beneath swampy sea-marshes and lagoons, receiving sediment from large rivers flowing out of the low-lying ancestral Nevadan mountains. Dinosaurs are extinct. The San Gabriel Mountains begin to form.
At the beginning of this era, what will become the Los Angeles area lies beneath a deep, subtropical sea and, before the San Andreas Fault begins its push, is located about 100-150 miles southeast of where it is today. The land later begins to emerge, with the local shoreline running along the San Gabriel, Santa Monica and Santa Ana Mountains and the Covina Hills. These ancient hills, ripe with volcanic activity, rise to no more than an elevation of 1,000 feet. Dry land around the submerged Los Angeles Basin becomes subtropical, receiving about 30-40 inches of rainfall a year. It is covered with scrub forest and inhabited by ancient horses, rhinoceros and camels.
Los Angeles area hills are forced upwards in height to become mountain ranges. The sea level drops.
Large mountain ranges now are present and the Los Angeles Basin, formed from accumulating sediment deposits, slowly rises from the sea. The shoreline recedes to about where it exists today. The climate is cooler and moister than present, similar to that of present-day Monterey Peninsula, with glacier activity along the peaks of the San Gabriel and Santa Ana Mountains and Redwoods growing in the Santa Monica Mountains.
The Los Angeles Basin is a large grassy, brush-covered and marshy plain, roamed by Saber-Tooth Tigers (or Saber-Tooth Cats), Harlan's Ground Sloth, Dire Wolves, Western Horses, Ancient Bison, Yesterday's Camel, Short-Faced Bears (Artodus Simus), Columbian Mammoths and American Mastodons. A number of these animals find themselves unwittingly trapped in the tar fields of what will be known as the La Brea Tar Pits.
Animals named in the previous period along with many other concurrent species are now extinct in Southern California. The Los Angeles Basin is covered in grassy plains with scattered strands of junipers and cypress trees, streams, marshes, small lakes and ponds. Humans have settled in the coastal areas of the Los Angeles area, particularly the the Ballona wetlands.
For reasons fair or foul, the body of a young women who would later become known as La Brea Woman, is left in La Brea Tar Pits area of Los Angeles. Her remains are found about 9,000 years later in 1914. This period is perhaps the same period in which Los Angeles Man lives.
The Chumash engage in sophisticated basketry and make use of asphaltum (tar) for water-proofing. There is increased reliance on hunting and the more sophisticated technological developments such as the throwing stick, knives, drills, and fish hooks. Burials include more artifacts.
Humans appear to have abandoned the Los Angeles area. Modern archeologists speculate that dramatically dropping sea levels turn the marshy, marine life-rich wetlands, important to local human habitation, into “a brackish water lagoon."
Human settlement again reappears in the Los Angeles area, in the area of the Ballona wetlands. These ancestors of the Chumash engage in warfare and trade and form alliances. There is increased division of labor and craftsmanship. Funerary practices are more elaborate. Relying heavily on marine life for food, they practice little to no agriculture.
The first of the native people later known as the Gabrielino (or Tongva) arrive in what will become Los Angeles County from the Mojave area, displacing many of the earlier residents related to the Chumash.
The Chumash, still present in in what will become the Malibu area and just north of there, engage in sports competitions and development of musical instruments. Trade in the region is widespread, including the use of shell beads for money.
About 25 Gabrielino villages exist in what will become Los Angeles County. The population is about 300 to 500 people.
Juan Rodriguez Cabrillo lands on Catalina Island, the first European contact with the future Los Angeles. Seeing at a distance the Indian campfires at Santa Monica Bay, he names it Bay of Smoke.
Father Crespi, a member of a Spanish land expedition led by Captain Fernando Rivera Y Moncado, first makes record of Los Angeles (August 2). Local Indians, from the nearby village of Yang-Na (located near what is now the Civic Center) greet the party. A series of earthquakes are experienced by the expedition while in the Los Angeles area.
Fathers Pedro Cambon and Angel Somera establish the Mission San Gabriel Arcangel (Saint Gabriel the Archangel) at its first location in modern-day Montebello (September 8).
Padres are forced to move the Mission San Gabriel Arcangel to its present location in modern-day San Gabriel due to flooding at the original site.
Juan Bautista de Anza stops at the Mission San Gabriel Arcangel leading a band of the first 30 Spanish families to colonize California. They are enroute to establish a settlement in the San Francisco area.
Governor Felipe de Neve issues instructions for the establishment of a new pueblo (town) with the proposed name El Pueblo de la Reina de Los Angeles Sobre el Rio de la Porciuncula (August 26). It becomes known as El Pueblo (The Town). The first Indians are baptized at the Mission San Gabriel seven years after the establishment of the mission.
Governor Felipe de Neve visits the future site of the new pueblo to clear the land and mark it off. Forty-four men, women, and children begin life at the new pueblo, El Pueblo de Nuestra Señora la Reina de los Angeles de Porciuncula (The Town of Our Lady the Queen of the Angels of the Porciuncula River)(September 4). Only two of the original adult settlers are white Spaniards. The other settlers are of Indian, Mestizo, African, and Mulatto descent. Twenty-two are children.
Father Junipero Serra arrives in El Pueblo to condemn the moral condition of its residents.
The first three land grants in the Los Angeles area are given to three soldiers, Juan José Dominguez, Manuel Nieto, and José Maria Verdugo. These are Los Angeles’ first ranchos.
José Vanegas, one of the original settlers and an Indian, is appointed Alcalde (mayor) of El Pueblo.
Construction begins on what would later become known as the Gage Mansion in Bell Gardens and the oldest surviving home in Los Angeles County. The home later becomes part of the Rancho San Antonio land grant given to Don Antonio Maria Lugo in 1810. (Special thanks to Shane P. Kimbler of Bell Gardens for this information)
The Mission San Fernando Rey de España (Saint Ferdinand, King of Spain) is founded by Father Lasuén (September 8).