VISUALIZATION OF GEOLOGIC TIME Demonstration

Ga = giga annum = billion years = 1,000,000,000 years = 10⁹ years

Ma = mega annum = million years = 1,000,000 years = 10⁶ years

12 to 15 Ga - origin of the Universe

4.55 Ga - origin of solar system and Earth

4.50 - formation of the Moon

~3.96 Ga - oldest rocks on Earth dated so far

~3.8 Ga - first evidence of life on Earth

570 Ma - first animals with hard shells

245 Ma - Permian extinction

65 Ma - K-T extinction (dinosaurs)

4-5 Ma - ancestral humans

~500,000 years - Homo sapiens

~12,000 years - end of Ice Ages

The landscape you see in and around the San Fernando Valley is the product of several different processes operating on vastly different time scales.

-- Uplift of the Santa Monica and San Gabriel Mountains)

-- Erosion of large canyons (e.g., Grand Canyon/Sabino Canyon)

-- Major evolutionary changes in plant and animal species

-- Oxygenation of the atmosphere that we depend on for breathing (Note that this process began billions of years ago)

-- Formation of the hydrosphere through volcanic degassing

-- Accumulation of deep-water sand deposits that now form the Simi Hills

-- Accumulation of marine diatoms that now form the white rocks near Pierce College

-- Climate changes (e.g., Ice Ages)

-- Vegetation changes (i.e., oak trees in the Tucson Basin, not just in the mountains as today)

-- Archaeology (the oldest site in California is 11,500 years old)

-- Initial filling of the San Fernando Valley groundwater aquifer

-- Formation of fertile soils that can support farming and forest

-- Formation of desert pavement and desert varnish

-- Wave-cut terraces along our coast, especially on Palos Verdes

-- Accumulation of land-mammal bones in the La Brea Tar Pits

-- Human impact

Growth of a city (e.g., Los Angeles)

Depletion of groundwater reserves and open spaces*

Pollution of the hydrosphere and atmosphere*

Extinction of plant and animal species*

Soil erosion*

Habitat destruction*

Formation of the Salton Sea

-- Erosion of arroyos (gullies) along the Santa Clara River

-- Individual lifetimes of most plants and animals

-- Channelization of the Los Angeles River within concrete walls

*Compare the amount of time it takes these critical resources to form naturally with how rapidly humans have impacted them.

To gain a sense of how long a million years is and how slowly some of the above processes operate, here is a comparison of some things which are truly a million of with things you might have thought that were a million of.

-- Atoms in the smallest living cell

-- Sand grains on Santa Monica Beach

-- Atoms of iron in one steel nail

-- Poppies near Lancaster in the Spring

-- Miles to Mars

-- Diatom fossils in a hand specimen if diatomite

-- Coccolith fossils in a piece of chalk

-- Personal computers in the United States

-- Cells in your body

-- Dollars added to the U.S. federal budget deficit each hour

-- Gallons of water used in Los Angeles every day

-- Hairs on your head

-- Words in a book (even War and Peace or your Geology text)

-- Pine needles on an average-sized pine tree

-- Miles to the Moon

-- Number of "thank yous" you will say in a lifetime.

-- Privately-owned swimming pool in Los Angeles County

-- Students in lower-division geology courses each semester at CSUN

-- Miles to San Francisco

-- Years since your great-great-great-great-great-great-great-great-great grandmother lived