Flag Hill

Introduction and Overview The Walk Topographic Map USGS information on Topographic Maps Locating your position on a topo map Flag Hill Sunol Rocks Serpentine Description

Geologic Map Types of rocks at La Costa area Franciscan Rock Serpentine Rocks Sedimentary Rocks Landslides/ Mudflow Strike and Dip symbols Age of Sunol Rocks Faults (movement and types) Direction of rocks The Preliminary Geologic Map/ La Costa Valley Quardrangle

Students watching Ms. Hanna instructing about rock formation.

Welcome to the East Bay Regional Park district's Ohlone Wilderness Trail, a gateway to 28 miles of scenic wilderness and thousands of years of natural history. The Ohlone Wilderness Trail links four Regional Parklands in southern Alameda County from west to east; Mission Peak Regional Preserve in Fremont, Sunol Regional Wilderness south of Sunol, Ohlone regional Wilderness and Del Valley Regional Park south of Livermore. The remote and beautiful lands are the domain of abundant wildlife, including endangered species such as the bald eagle. Eagles, red-tailed hawks and turkey vultures ride the thermals above undisturbed canyons and ridges where the mountain lion and bobcat prowl. The land is studded with oak and bay, carpeted with springtime wildflowers, and mantled briefly in white after winter storms. Elevations range as high as the 3,817 - foot Rose Peak, only 32 feet lower than Mt. Diablo. From the ridges and peaks of the Ohlone Wilderness Trail, the energetic hiker is rewarded with panoramic views of the San Francisco Bay area and central California ranging eastward to the Sierra Nevada (on a clear day). Information from Ohlone Wilderness Regional Trail Permit. Permits are only $3.00 at the front gate.

Lets get started! The meeting place is located at the picnic benches. Turn left after you go past the rangers gate house, you will then see the picnic benches to the left. Instructor Ruth Hanna starts on time just as she would in class. First on the agenda is the topographic map. This is a great learning experince if you have never taken a geology lab. We estimated the walk to be around 2.2 miles and can take 3 to 4 hours depending on stopping and discussions about the different rock formations. We will be traveling along the Indian Joe Creek trail. Drinkable water is not avalble along the trail. The main route crosses Alameda Creek and parallels Indian Joe Creek. You will travel on a drainage divide and see the under cutting of the two streams coming together. The trail will take you through a dense forest of black oak and live oak. The trail climbs with a small amount of altitude. You will walk across serpentine grasslands with interesting rock formations and high profusely flowered meadows when in season.

 

Profile -- its not really this steep!

This is a topographic profile construction of the walk. Understand that you can exaggerate the profile of the vertical scale. This VERTICAL exaggeration is 3.2 times real life -- therefore, the hills look much steeper than they actually are.

Topographic Map

The strike and dip symbols on the topographic map give you the understanding of which way the water shedds direction is traveling down hill. In other words, it is the slant of the downward direction of the hills run off water. Ms. Hanna is showing you a demonstration of which way you place your hands to visualize this in action. The long line is the direction you place your hand. The small line is the way your thumb is directed to tilt your hand.

Sunol Reginal Park Map

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