This trail is now temporarily closed. The geologic point of interest in the lesson discussed in the description is still visible from the front gate of the Vulcan Materials yard. Observations can still be made, and the questions can still be answered.
*Geology of the Quarry*
Azusa Rock (Vulcan Materials Quarry) is a "hard-rock" quarry. The rocks mined here are called aggregates. Construction aggregates mined from this facility are of the highest quality in the country. The strength of these materials meets or exceeds the strictest specifications for state and federal highway construction in California.
Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, and slag. Slag is the rock and stone matter separated from the refining process of metal. Aggregates are the most mined materials in the world. Aggregates are a component of composite materials such as concrete and asphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material. Aggregates are also used as base material under foundations, roads, and railroads. The aggregate rocks are small in size, typically 3/16 of an inch in diameter per rock is considered fine aggregate. Aggregates can be sedimentary rock, metamorphic rock, or igneous rock. Sedimentary aggregates are closer to the surface and therefore more cost effective to mine. Overall, this quarry mines the rock from the hillside, crushing them to produce aggregates for construction materials. If you hike this newly opened trail during a work day, you may hear some loud 'booms' as the hillside is being broken down and mined.
*Logging Requirements*
1. The name of this earthcache
2. The number of people in your party
3. Estimate the height of the carved away ridge to the east.
4. Would you guess that this is sedimentary, metamorphic, or igneous rock that is being mined? Why?
*Sources*
-http://www.azusarock.com/
-http://en.wikipedia.org/wiki/Construction_aggregate
-http://dictionary.reference.com/browse/slag
-http://www.ce.berkeley.edu/~paulmont/CE60New/aggregates.pdf
-Angeles National Forest Fish Canyon Informational Signs