Although most people have likely never heard of the small town of Agua Dulce, they probably HAVE heard of the incredible geological formation known as Vasquez Rocks. Vasquez Rocks is located in the heart of this small high desert town, but that is not what this earth cache is about. This earth cache is about an additional iconic geological feature of Agua Dulce known as Saddleback Mountain. Once you spot this incredible formation you will know exactly why it is referred to as saddleback. The mountain consists of two crested basalt ridges (the horn and the cantle), with exposed sandstone in between (the seat), which forms a saddle-like shape.
BASALT: is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as lava flow.
While volcanic activity has long since ceased in Southern California, it has left it's mark. From cinder cones in the Mojave Desert, and geothermal vents in the imperial valley, to basalt in the Antelope and Santa Clarita Valleys, volcanoes have played a large role in the geology of Southern California. In the Agua Dulce area, the base of the Vasquez formation (and surrounding areas - Saddleback Mountain) has basalt dating back to the Oligocene Epoch (about 30 million years ago). I suppose you could say that this is the oldest saddle in town. Nyuk Nyuk.
Thank goodness a real saddle doesn't have a horn and cantle made of basalt. Ouch. Although it is important that the horn and cantle be strong and sturdy.... much like basalt. The seat of a saddle, however, should feel entirely different. No one wants to ride a saddle with a hard and unyielding seat. That leads us to the seat of Saddleback Mountain.
SANDSTONE: A sedimentary rock composed of sand-size grains of mineral, rock, or organic material. It also contains a cementing material that binds the sand grains together and may contain a matrix of silt or clay size particles that occupy the spaces between the sand grains. Sandstone is one of the most common types of sedimentary rock.
Due to the softer, more brittle nature of sandstone it is very likely that the seat of Saddleback Mountain was formed over millions of years of wind and rain erosion. Not such a bad thing if you plan to ride on that saddle for extended periods of time. Nyuk Nyuk (again).
LOGGING REQUIREMENTS: Please email the answers to the following questions -
1.) From your vantage point (facing Saddleback Mountain) which part of a "real" saddle do you think the South ridge represents? The North ridge? (Cantle, Horn, or Seat)
2.) During what time period in our Earth's history are the basalt rock formations in this area believed to have been formed? 3.) What is the most common type of sedimentary rock?