Background Information:• Glass Mountain was a volcano a long

time ago. When it erupted the lava soon cooled and formed obsidian.

• Obsidian is a black, shiny rock that almost looks like glass. Wappo Indians, a native tribe, used obsidian by carving it into a point called an arrowhead.

• Glass Mountain is on N Silverado Tr. Its just passed Deer Park Rd. Many people have passed it going to Calistoga on Silverado Tr.

Introduction Cont.Introduction Cont.

Testable Question:• What is the distribution pattern of obsidian

around Glass Mountain?Hypothesis:• Our hypothesis is that the most obsidian

will be on the east side of Glass Mountain. (on Deer Park Rd.)We think this because it’s the steepest slope and all the obsidian will tumble to the bottom of the hill.

Experimental Variables: The experimental variables are the

different test sites.Constant Variables: The constant variables are Glass

Mountain and the amount of the samples.

• Shovels• Compass • Double-sided plow• Gloves• Scale • Plastic bags• Sharpie/ pencil• Metal sieve• Big metal spoon• Binder paper• Newspaper• Map

1)Map out area. 2)Indentify study sites. 3) Collect at least 1 kg. of test soil

into the bag. 4) Label the bag with the place the

sample was taken. 5) Repeat procedures numbers 2-4

until there are nine soil samples including the control.

• 6) Dry the soil samples in the sun for 24 hours to get rid of excess moisture.

• 7)Use a kitchen scale to weight 1 kg of each soil sample.

• 8)Filter each soil sample using 1 centimeter square metal sieve to separate the obsidian.

• 9) Weigh the obsidian left in the sieve.• 10) Repeat steps #7-9 for each sample.• 11) Record results.

Observation and DataDate: Soil

Sample:Total Weight :

Weight Of Obsidian:

% of Obsidian in soil:

3/18 Titus Vineyards

1 kg. 0.25 25%

3/18 South-East Glass Mountain

1 kg. 0 0%

3/18 North Side Glass Mountain

1 kg. 0.67 kg. 67%

3/18 Hillside- Lodi Lane

1 kg. 0.06 6%

3/18 End of Swanston Rd.- hilltop

1 kg. 0.05 5%

3/18 East Deer Park

1 kg. 0 0%

Observation and Data Cont.

Date: Soil Sample:

Total Weight:

Weight of obsidian:

% of obsidian in soil :

3/18 North-West Swanston Rd. Hillside

1 kg. 0.125 12.5%

3/18 North-west wall, front of Duckhorn winery

1 kg. 0.750 75%

3/18 Control: Markham Vineyards West of Napa River

1 kg. 0 0%

Data GraphData Graph

One of our observations based on the soil samples is that not all sides of Glass Mountain have the same concentration of obsidian.

We found that two of the highest samples of obsidian were found at the North-West side of the mountain.

Soil samples and visual observations on the North West side showed that Glass Mountain has contributed to the distribution of obsidian spreading towards the Napa River.

We found no obsidian in the East and South-East of Glass Mountain.

Our control soil sample, west of the Napa River, on Markham Winery did not have any obsidian.

Conclusion

• From analysis of the soil samples we discovered that our hypothesis was incorrect. Our hypothesis was that most obsidian would be found on the east side of Glass Mountain. It turned out obsidian was found mostly at the North West side of the mountain. We think this is because: a) there is more concentration of obsidian on the North side of Glass Mountain; b) the north side of Glass Mountain may be more susceptible to weathering and erosion and thus, obsidian is found at the upper soil surface; c) construction or human activity on the East side caused it to be moved or turned under the soil.

• We think this project has contributed to a better understanding of: a) the distribution of obsidian at Glass Mountain b) the importance of Glass Mountain as a source of obsidian and its influence in the settlement of local Native Americans.

• Were we to repeat this experiment we would make sure to include more soil sampling and interviews with local historians and geologists.

Works-Cited-

Google Maps. March 10, 2009. http://maps.google.com

United States Geological Survey. March 10, 2009. http://geomaps.wr.usgs.gov

Stone Quarries and Beyond. March 10, 2009. http://quarriesandbeyond.org

CA HomeTownLocator. March 10, 2009. http://california.hometownlocator.com

We would like to thank Pierette Titus for all of the many things she helped us with. This experiment wouldn’t have been possible with out her.