Within the Dave Moore Nature Area, along the Dave Moore Trail there are many fabulous sights to see. The beauty of nature surrounds, the river and sandy beach are just a short walk away, dinosaurs inhabit the walking trail (or at least little plastic dinosaur figures left by previous hikers making for a fun little hiking game of “how many dinsaurs can you spot.”). But most interesting is this wonderful geological feature known as “Mushroom Rock”, two stacked granite boulders with a softer layer of decomposed granite in between that has been weathered and eroded over time.
Today you will head down the trail to Mushroom Rock and answer a few questions. Enjoy.
REQUIREMENTS:
- How many are in your group, caching names please, only one set of answers need be sent.
- Why is this called Mushroom Rock? (Observationally you should get this)
- Describe the color difference between the granite layers, let’s call them Lower Layer, Middle Layer, Upper Layer. Do you notice any other interesting features on Mushroom Rock (describe them)?
- What kind of erosion do you think most helped to affect and form Mushroom Rock?
- OPTIONAL: Take and post a picture from along you little hike (PLEASE DO NOT POST PICTURES OF Mushroom Rock SPECIFICALLY as it may spoil the hike for future cachers).
INFORMATION:
Dave Moore Trail Loop is roughly a 1 mile hiking loop that brings you to the South Fork of the American River. Mushroom Rock is along the trail and observations can be made from the trail.
ABOUT THE NATURE AREA AND THE TRAIL:
What you need to know:
- Dave Moore Nature Area is a Day-Use area only. No overnight camping.
- No equestrian use on trail.
- CLOSED to all hunting and target shooting.
- Potable water is not available. Bring your own water.
- Please be aware that there are bobcats and rattlesnakes in the area.
- Fireworks are prohibited.
- Firewood cutting and collection is prohibited.
- A Special Recreation Use Permit is required for all commercial, organized groups, or competitive activities.
- Hiking on Public Lands
GRANITE:
Granite is the most abundant rock in the Earth continental crust. It is a common and often used building material, used in the construction of buildings, bridges, statues, monuments, paving, countertops, flooring, stairs, and many other things. Granite is mostly composed of interlocking feldspar crystals, quarts, and other minerals. Granite is generally about 5% Feldspar, 20% Quarts, and 15% other minor minerals. The minor essential minerals of granite may include muscovite, biotite, amphibole, or pyroxene. This composition and lead to granite being different colors such as: red, pink, grey or white with dark mineral grains visible. Some geological features commonly seen or found in granite can include: crystals/crystal deposits, quartz deposits/quartz veins, marbling, layering, sheeting, and inclusions. Granite tends to be a course-grained or medium-grained texture. It is an igneous rock and the most common plutonic rock found in the Earth’s crust. It is formed when the magma cools at depth.
TYPES OF EROSION:
- Water erosion: Water erosion occurs when water moves over rock and soil, rubbing and eating away at it over time. This can happen with rain, or with other moving water sources like streams, creeks, and rivers.
- Sheet and Rill erosion: Sheet erosion occurs when a thin layer of topsoil is removed over a whole hillside. Rill erosion occurs when runoff water forms small channels as it concentrates down a slope.
- Scalding: Scalding can occur when wind and water erosion removes the top soil and exposes the deeper subsoil.
- Gully erosion: Gully erosion happens when runoff concentrates and flows strongly enough to detach and move soil particles.
- Tunnel erosion: Tunnel erosion is the removal of subsoil, the underground movement of water through the soil.
- Wind erosion: Wind erosion occurs when strong winds blow over soil and across harder rock and/or soil.
Come and have some fun, take a short little walk in nature, do some geocaching, perhaps count dinosaurs. Get out and see the sites nature offers us.
SOURCES:
https://www.blm.gov/visit/dave-moore-nature-area
https://www.britannica.com/science/granite
https://hardscape.co.uk/granite-facts-geology/#:~:text=This%20rock%20is%20primarily%20composed,visible%20to%20the%20unaided%20eye
https://www.qld.gov.au/environment/land/management/soil/erosion/types