Berkeley Hills

From Wikipedia, the free encyclopedia

The Berkeley Hills are a range of the Pacific Coast Ranges which overlook the northeast side of the valley in which San Francisco Bay is situated. They were originally called the Contra Costa Hills, but with the establishment of Berkeley and the University of California, the current usage was applied by geographers and gazetteers.

Contents 1 Geology 2 Development 3 Usage 4 Climatic effects 5 References

[edit] Geology

Tectonically, the Berkeley Hills are bounded by the Hayward Fault along their western base, and the Wildcat Fault on their eastern side. The highest peaks are Vollmer Peak (elevation 1,905 feet/581m), Grizzly Peak (elevation 1,754 feet/535 m) and Round Top (elevation 1,761 feet/537m), an extinct volcano, and Willhelm Rust Summit 1,004 feet.

Vollmer Peak was named for the first police chief of the City of Berkeley, August Vollmer. It was formerly known as "Bald Peak".

[edit] Development

Much of the western slope of the Berkeley Hills is occupied by densely-built residential neighborhoods of mostly single family homes, except on the land of the University of California. Most of the streets are narrow and many tend to follow the contours of the land, although there are at least two streets, Marin Avenue and Moeser Lane, which go directly up toward the ridgeline. Other roads to the ridgeline wind their way up the various canyons. Near the ridgeline and generally following its contour are Grizzly Peak and Skyline Blvds.

The eastern slope of the Berkeley Hills, by contrast, is mostly preserved or partially developed wildland, a good portion of which is owned by the East Bay Regional Park District and the East Bay Municipal Utility District (EBMUD).

The Berkeley Hills are pierced by several tunnels. Two of these are aqueducts of EBMUD. The Berkeley Hills Tunnel serves the Pittsburg-Baypoint line of the Bay Area Rapid Transit (BART) system. The three bores of the Caldecott Tunnel carry State Highway 24 between Oakland and Contra Costa County.

[edit] Usage

It is common in recent years to hear the term "Oakland Hills" applied to that section of the Berkeley Hills which run along the east side of Oakland, but as a proper name or officially-recognized toponym, it is incorrect. However, the exact southern terminus of the usage "Berkeley Hills" is unclear. It does not, in any case, correspond to any political boundaries, only to a geographic feature (much as "San Francisco Bay" is not limited to that stretch of the Pacific inlet within the bounds of the City and County of San Francisco). The same ridge does in fact extend south through Oakland and San Leandro to the drainage of San Leandro Creek called Castro Valley, and geologically, continues southward above the line of the Hayward Fault. In the section above East Oakland to Castro Valley, the ridge appears on most maps as the "San Leandro Hills".

The northern limit of the proper name "Berkeley Hills" is likewise unclear, but the same ridge runs continuously right up to the shoreline of San Pablo Bay north of Richmond. The eastern slopes of the Berkeley Hills lie entirely outside of the city of Berkeley within Contra Costa County.

Another common informal usage is East Bay Hills, but its application to any particular range east of San Francisco Bay is very unclear. In some contexts, it may refer collectively to all of the ranges east of the Bay, from the Berkeley Hills to the Diablo Range and all the ranges between.

[edit] Climatic effects

The Berkeley Hills affect the local climate by their elevation and situation. The oceanic marine layer which is most developed during the summer months is usually less than 2,000 feet deep and thus is blocked by the range. This produces a "fog shadow" effect on the areas directly east which are consequently markedly warmer than areas west of the hills. The westerly wind which carries the marine layer through the Golden Gate typically splits its flow as it hits the Berkeley Hills producing a southerly wind from Berkeley northward and a northerly flow in the direction of Oakland. In winter during spells of tule fog inland, the reverse occurs, with the fog usually confined to areas east of the hills.

The Berkeley Hills also have an effect on rainfall. When the wind direction is oriented perpendicular to the hills (southwest wind) during a rain event, air is forced to rise, cooling and condensing additional moisture, increasing the amount of precipitation along the western slopes, and leaving areas east of the hills relatively drier.

In winter, an especially cold storm will deposit wet snow on the peaks. A particularly favored spot is along Grizzly Peak Boulevard in the vicinity of the Miniature Train Ride and Grizzly Stables (Lomas Cantadas Road).

In the spring and fall, strongly sinking air from aloft combining with inland high pressure periodically sends hot, dry, and gusty winds across the ridges of the Berkeley Hills, posing a significant fire danger which in the 20th century produced several wildfires, two of which caused major damage to Berkeley and Oakland. (See 1923 Berkeley Fire and 1991 Oakland firestorm).

[edit] References

• USGS GNIS: Berkeley Hills
• The California Earthquake of April 18, 1906: Report of the State Earthquake Investigation Commission, Andrew C. Lawson, chairman, Carnegie Institution of Washington Publication 87, 2 vols. (1908) - Available online at this USGS webpage.