FIELD STUDYSan Luis Obispo, CA

By Sarah Diekneite

Bishop’s Peak

What: A dormant volcano that is now an extremely popular hiking spot

Who: Partially owned by the Bishop Peak National Reserve and the Sierra Club

Where: The central coast town of San Luis Obispo, CA

When: The mountain was formed 20 million years ago. It was bought by the Bishop Peak National Reserve in 1977. (Felsman, 2008)

Exploration site:

The tallest of the “Nine Sisters”

History: Bishop’s Peak

• 20-25 million years ago, a chain of volcanic plugs, commonly referred to as the “Nine Sisters” were formed between Morro Bay and San Luis Obispo, CA

• Subduction occurred as the widening Atlantic Ocean pushed North America

• A June 1992 records check with the California Archaeological information Center (UCSB) confirmed that mortar sites exist throughout the high meadows of Bishop Peak. (Felsman, 2008)

View from halfway up Bishop’s

Bishop’s Geological Formations

• Because it is so weathered, the rocks of Bishop’s Peak appear to be whitish granite, but are actually gray and contain a type of silica called Rhyodacite

• Weathering over the past millions of years has cracked the mountain in many places, especially near the top, causing boulders and land slides. This means that the present peak is now a lot shorter than it used to be. (Felsman, 2008)

• Many dike injections of magma can be noticed throughout all of the “Nine Sisters,” especially in Bishop’s. (Felsman, 2008)

• Other volcanic features are present on the sides of the peak as well, including landslides, avalanches, and exfoliation weathering.

Dacite

Dacite is an igneous, volcanic rock. It is composed of Andesite and Rhyolite.

Bishop Peak is primarily composed of dacite. Magma from its days as a volcano welled up underneath a layer of softer rock and solidified. The softer overlying rock has eroded away over the years, leaving the dacite.

Serpentine

Serpentine is a metamorphic rock that is formed at low-temperatures. It is created through a reaction involving heat and water in which low-silica mafic and ultramafic rocks are oxidized.

Serpentine is the second most common rock found on the “Nine Sisters.” I was lucky enough to find one large sample on the peak, and also some stones of Serpentine at the Learning Pine Arboretum.

Bishop’s Peak Today

• 1,559 feet above sea level• Currently, there are three main trailheads• On February 15, 1968, succeeded in obtaining its designation as

State Historical Landmark #821.• The Peak is in danger from hikers and climbers making their own

paths, which leads to excess erosion• Animals such as mountain lions, coyotes, bobcats, deer, turtles,

frogs, and Garter snakes are very common (Ernest & Allen, 1995)

• Vegetation includes grassland, oak woodland, and chaparral that provide a wide range of habitats.

The Learning Pine ArboretumExploration site:

Cal Poly, San Luis Obispo

What: An outdoor “living laboratory” of beautiful and interesting landscape plants

Who: Run by the Environmental Horticultural Science facility

Where: Located on five acres of Cal Poly’s campus, overlooking the Santa Lucia Mountains

When: I visited on July 22, 2011

Why: To display sunning landscapes teach about plants from around the globe

Overview: The Arboretum

• The Arboretum is nestled on a plot of rich soil, surrounded by natural, medium sized mountains

• The natural landscape includes many types of rock formations, nonswampy plants and trees (specifically lots of oak), and short, dry shrubs.

• Aloe plants are also referred to as the “healing plant”• They can live for up to 25 years (Aloe plant information, 2011)

• Its leaves are extremely succulent, absorbing and containing juices known best for helping to heal burns

Aloe

California Buckeye Tree

• The California Buckeye tree’s scientific name is Aesculus californica

• It is very unique in that it loses its leaves during the summer, rather than in the fall

• In the winter, it regains its bright green leaves

• In the spring, it produces plumes of white and pink flowers

Yellow Swallowtail

• Yellow Swallowtails are extremely common, found on every continent except Antarctica

• They come from the butterfly family Papilionidae.

• There are currently 550 known species in the Papilionidae family (Dodie,

2004). Many of these species have developed and evolved out of others.

• This particular specimen had a wingspan of approximately three or four inches wide, when fully opened.

CitationsAloe plant information. (2011). Retrieved from http://freealoeplant.tripod.com/

Dodie. (2004). Yellow swallowtail butterflies . Retrieved from http://www.nature-and-flower-pictures.com/yellow-swallowtail-butterflies.html

Ernest & Allen. (1995). History of morro rock and the nine sisters . Retrieved from http://www.morrobay.com/rock.htm

Felsman, G. (2008). The nine sisters of san luis obispo county. Retrieved from http://santalucia.sierraclub.org/ninesis.html

Wikipedia- Bishop’s Peak. Retrieved from http://en.wikipedia.org/wiki/Bishop_Peak_%28California%29

Picture Links:http://detailsinlandscape.com/about_ushttp://www.rockclimbing.com/images/photos/assets/6/269246-largest_5736.jpg