Mount Hamilton (California)

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Mount Hamilton (Copernicus Peak)
Lick Observatory is visible atop Mount Hamilton; hillsides show typical summer golden (dry) vegetation
Elevation	4,360 ft (1,330 m)
Location	California, USA
Range	Diablo Range
Prominence	3,120 ft (950 m)
Coordinates	37°20.81′N, 121°37.81′W
Topo map	USGS Lick Observatory
Age of rock	Upper Cretaceous
First ascent	1861
Easiest route	road

Mount Hamilton is a mountain in California's Diablo Range. In 1861, while working for Josiah D. Whitney on the first California Geological Survey, William H. Brewer invited local San Jose preacher (and Brewer's personal friend) Laurentine Hamilton to join his company on a trek to a nearby summit. Nearing completion of their journey, Hamilton, in good humor, bounded for the summit ahead of the rest of the men and claimed his stake. In fact, Brewer suggested the mountain be named after Hamilton only after Whitney declined to have the mountain named after him (a different mountain was later named Mount Whitney).

Mount Hamilton is the tallest mountain overlooking Silicon Valley, and is the site of Lick Observatory, the first permanently occupied mountain-top observatory.^[1] The various summits along its mile-long summit ridge have been given astronomy-related names. The highest is 4,360-ft (1,330 m) Copernicus Peak; 4,250 ft (1,295 m) Kepler Peak and 4,213-ft (1,284 m) Observatory Peak follow. The latter was more than 30 ft (10 m) taller before it was leveled during the construction of the observatory in the 1880s. The asteroid 452 Hamiltonia, discovered in 1899, is named after the mountain. Golden Eagle nesting sites are found on the slopes of Mount Hamilton.

Numerous times each winter, the snow level drops low enough for Mount Hamilton (left) to receive as much as a foot of snow for a day or two.

[edit] Climate

These mountains are high enough to receive snowfall in the winter, perhaps up to a dozen times. Occasionally, when a cold, wet storm comes in from the Gulf of Alaska or Canada, Mt. Hamilton and the surrounding peaks get serious snowfall. In February 2001, 30 inches (76.2 cm) of snow fell, and in March 2006, the peak was left with over a foot of snow (30 cm) in one night.

The National Weather Service has had a cooperative weather station on the summit of Mount Hamilton almost since the time that the Lick Observatory opened. It has provided a glimpse of the extreme weather conditions that occur on the Diablo Range, especially in the winter months.

January is usually the coldest month on Mount Hamilton with an average high of 49.4°F (9.7°C)and an average low of 37.5°F (3.1°C). The warmest month is usually July with an average high of 78.2°F (25.7°C) and an average low of 63.1°F (17.3°C). Due to frequent thermal inversions during the summer, it is often warmer on Mount Hamilton than in San Jose. The record high temperature of 103°F (39.4°C) was on August 5, 1978. The record low temperature of 7°F (-13.9°C) was on December 21, 1990. The average days with highs of 90°F (32°C) or higher is 4.3 days. The average days with lows of 32°F (0°C) or lower is 50.6 days.

Annual precipitation averages 23.73 inches (60.27 cm). Measurable rainfall occurs on an average of 71.9 days each year. The most rainfall in a month was 12.13 inches (30.8 cm) in February 1998; no rainfall has been common during the summer months. The maximum rainfall in 24 hours was 6.87 inches (17.4 cm) on December 23, 1955.

Annual snowfall averages 10.4 inches (34.1 cm). The maximum snowfall in a month was 32.0 inches (81.3 cm) in March 1982. The 24-hour maximum snowfall of 14.0 inches (35.6 cm) occurred on February 18, 1990. The deepest daily snow depth was 18 inches (45.7 cm) in March 1976. Measurable snow has been recorded in every month from November through June.

California State Route 130 at the foot of the Diablo Range Mountains looking towards Mount Hamilton and the Lick Observatory.

[edit] Mount Hamilton Road

The twisting, curving 19-mile (30 km) Mt. Hamilton Road (part of California State Route 130) is popular with bicyclists and motorcyclists. Built in 1875–76 in anticipation of the observatory, and the need to carry materials and equipment up the mountain in horse-drawn wagons, the grade seldom exceeds 6.5 percent. The road rises a total of 5,000 ft (1,500 m) in three long climbs from San Jose to the mountain top. In addition to its challenging ride, it is sparsely traveled over most of its length and provides spectacular views of San Jose and the rest of the Santa Clara Valley below. These view do not come without a price, as numerous accidents occur on the road each year. Whenever it snows on Mt. Hamilton, the road is closed until crews can clear the road of snow and black ice.

The 20-mile drive from Interstate 680 to Lick Observatory takes about 45 minutes.

The bicycle ride is about 19 miles each way, from the Alum Rock junction. The upward trek is interrupted by two descents, first into Grant Ranch county park, and again to cross Smith creek. Quimby Road offers a shorter way from San Jose to Grant Ranch, but is considerably steeper. The main observatory building has water, a few vending machines, restrooms and an opportunity to warm up on a cold day. If the time is right, there are also guided tours of the Lick telescope, and the gift shop may be open.

The road is advertised to include 365 curves, one for each day of the year. This is true, subject to definition of the term "curve." If the yellow line bends to the right, then straightens out, then bends to the right again, we regard it as one curve. If the yellow line describes an ess, on the other hand, it counts as two curves, regardless of how gentle the ess may be.

The road continues down the backside of Mt. Hamilton, through almost completely empty country, and eventually coming out at Patterson, in Stanislaus County. Shortly after the summit, one can turn to the north and proceed on Old Mines Road, which ends at Livermore. There are several cattle gates along this road and even a (paved) ford through a shallow stream. Traffic is light to nonexistent.

[edit] Geology and hydrology

Much of the foothill slopes of Mount Hamilton is underlain by Miocene age sandstone of the Briones formation: this bedrock is locally soft and weathered in the upper few feet, but grades locally to very hard at depth. Depth to groundwater on these foothill areas of Mount Hamilton is approximately 240 feet.^[3] The Babb Creek drainage comprises some of the watershed draining the slopes of Mount Hamilton. The Calaveras and Hayward active earthquake faults traverse the slopes of Mount Hamilton.

[edit] The community

Mount Hamilton has its own zip code, 95140; it is generally uninhabited open space with a population in 2000 of only 35. ^[4] The place also has its own police force (one officer, a member of the University of California police), but because there are not enough school-age children in 2006, the Mount Hamilton Elementary school has been closed.^[5]

[edit] See also

• Grant Ranch Park

[edit] Footnotes

1. ^ The Building of Lick Observatory
2. ^ "Climatography of the United States," National Climatic Data Center (www.ncdc.noaa.gov)
3. ^ C. Michael Hogan, Paul Hoffey et. al. al., Environmental Impact Report for the Aiassa Site off Mount Hamilton Road, Santa Clara County, Ca., Santa Clara County Document EMI 7364W1 SCH88071916, August, 1989
4. ^ ZIP Code 95140 Census Data
5. ^ Mount Hamilton Elementary School, currently no enrollment

[edit] External links

• Nature Conservancy's Mt. Hamilton project
• Visiting Mt. Hamilton/Lick Observatory
• Bay Nature article on Mt. Hamilton ridgelands

• USGS GNIS: Copernicus Peak
• PeakBagger.com: Copernicus Peak
• Maps and aerial photos
  • WikiSatellite view at WikiMapia
  • Topographic map from TopoZone
  • Aerial image from TerraServer-USA
  • Surrounding area map from Google Maps
  • Location in the United States from the Census Bureau