Brea's first Earthcache!
Some quick history:
From the posted coordinates, one can view what used to be a common sight back in the time of prosperous oil drilling in the small town of Brea. Now, with the city modernized and industrialized, this type of visible oil seepage is seldom seen. Although Brea still produces it, oil is no longer Brea's main revenue source. Observation of oil seeps provided much of the discovery of oil in California in the 19th century.
What you see:
From this posted set of coordinates, one can view the occurrence of some natural Petroleum Seepage. Under certain conditions, such as low pressure or flow, liquid or gaseous petroleum can escape from underneath the earth out into the atmosphere or onto the earth's surface. Petroleum seeps can occur both on land and offshore. These are beneficial spots to drill for oil (hence why this Earthcache is located in what was a bustling drilling town long ago). The oil escapes to the surface along the stratum, or the layers of sedimentary rock that have a change in physical appearance than those of the layer below it.
The oil seeps across the strata or in the cracks and fissures in the rock, or directly from an outcrop of oil-producing rock. The seepage is caused by a break in the seal that kept the underground reservoir covered up. The break releases pressure, yet adds buoyancy force to the petroleum. Buoyancy force is the force emitted by a liquid when an object is submerged, commonly the "upward pushing" of the liquid. When the cavern is broken, the rock causes the oil to exert force, pushing itself up to the surface. There are two types of oil seeps. The first is a moderate, low-intensity widespread seepage that happens until resealing of the cavern occurs. The second type is one in that the rocks fracture from the pressure placed on the seal, breaking the rocks entirely. This causes intense seepage in a centralized area until the pressure equalizes and the fractures and seal are plugged.
Logging as a find:
Based on your new geology knowledge of natural oil seeps and how they are caused, determine what kind of seep this is (breached seal with low-intensity flow, or fractured and broken rock with high-intensity flow).
E-mail with the following:
•The name of this Earthcache
•The number of people in your group
•Fulfillment of the above presented task
Respect your surroundings, have fun, and stay safe!
Sources
-http://www.britannica.com/EBchecked/topic/568446/stratumhttp://en.
-m.wikipedia.org/wiki/Petroleum_seep
-http://en.m.wikipedia.org/wiki/Buoyancy_force
-http://www2.southeastern.edu/orgs/oilspill/images/oil_seep_diagram.jpg