Earth Cache with a View EarthCache
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This cache will take you to one of my favorite places. There is a panoramic 360 degree view of Lake Mead, Boulder City, Henderson, and Las Vegas. There are also some high quality traditional caches in the area.
You can access this cache either by walking up the trail from Boulder City, or by driving up the Bootleg Canyon road and then hiking the trail over from the parking area at the top of the road. (the trail is limited to hiking only) I first found this spot when I was growing up here in BC. ( I won't admit how many years ago that was)
The coordinates given should take you to a park bench. Fell free to sit down and take a break. I would suggest that you bring water no matter what time of year but especially in the summer months.
As you sit there you will find 2 signs with information about the geology of the area. As you look at the sign you can then look out in that direction and see the Geological features mentioned (this is where the answers to the questions can be found.
As you look around you will be able to see the a variety of geologic features on the mountains around the valleys. These mountains were formed from seismic activity along with volcanic activity. For the purpose of this cache focus on the seismic activity... See the information below about Faults. (taken from Wikipedia)
Fault types
Geologists can categorize faults into three groups based on the sense of slip: a fault where the relative movement (or slip) on the fault plane is approximately vertical is known as a dip-slip fault where the slip is approximately horizontal, the fault is known as a transcurrent or strike-slip fault an oblique-slip fault has non-zero components of both strike and dip slip. For all naming distinctions, it is the orientation of the net dip and sense of slip of the fault which must be considered, not the present-day orientation, which may have been altered by local or regional folding or tilting.
Dip-slip faults
Dip-slip faults can occur either as "reverse" or as "normal" faults. A normal fault occurs when the crust is extended. Alternatively such a fault can be called an extensional fault. The hanging wall moves downward, relative to the footwall. A downthrown block between two normal faults dipping towards each other is called a graben. An upthrown block between two normal faults dipping away from each other is called a horst. Low-angle normal faults with regional tectonic significance may be designated detachment faults. A reverse fault is the opposite of a normal fault—the hanging wall moves up relative to the footwall. Reverse faults indicate shortening of the crust. The dip of a reverse fault is relatively steep, greater than 45°. Cross-sectional illustration of normal and reverse dip-slip faults A thrust fault has the same sense of motion as a reverse fault, but with the dip of the fault plane at less than 45°. Thrust faults typically form ramps, flats and fault-bend (hanging wall and foot wall) folds. Thrust faults form nappes and klippen in the large thrust belts. The fault plane is the plane that represents the fracture surface of a fault. Flat segments of thrust fault planes are known as flats, and inclined sections of the thrust are known as ramps. Typically, thrust faults move within formations by forming flats, and climb up section with ramps. Fault-bend folds are formed by movement of the hanging wall over a non-planar fault surface and are found associated with both extensional and thrust faults. Faults may be reactivated at a later time with the movement in the opposite direction to the original movement (fault inversion). A normal fault may therefore become a reverse fault and vice versa.
Strike-slip faults
The fault surface is usually near vertical and the footwall moves either left or right or laterally with very little vertical motion. Strike-slip faults with left-lateral motion are also known as sinistral faults. Those with right-lateral motion are also known as dextral faults. A special class of strike-slip faults is the transform fault, where such faults form a plate boundary. These are found related to offsets in spreading centers, such as mid-ocean ridges, and less commonly within continental lithosphere, such as the Alpine Fault, New Zealand. Transform faults are also referred to as conservative plate boundaries, as lithosphere is neither created nor destroyed.
Oblique-slip faults
A fault which has a component of dip-slip and a component of strike-slip is termed an oblique-slip fault. Nearly all faults will have some component of both dip-slip and strike-slip, so defining a fault as oblique requires both dip and strike components to be measurable and significant. Some oblique faults occur within transtensional and transpressional regimes, others occur where the direction of extension or shortening changes during the deformation but the earlier formed faults remain active. Oblique-slip faults can be further sub-divided into four types : right normal, right transverse, left normal, left transverse. The hade angle is defined as the complement of the dip angle; it is the angle between the fault plane and a vertical plane that strikes parallel to the fault.
Listric fault
A listric fault is a type of fault in which the fault plane is curved. The dip of the fault plane becomes shallower with increased depth.
Ring fault
Ring faults are faults that occur within collapsed volcanic calderas. Ring faults may be filled by ring dikes.
OK now that you have read the information you are ready to walk over to the signs and answer some questions.
1.) If you are facing West. Name the 5 major Geologic features listed on this sign.
2.) In the La Madre fault what is the name of the highest point?
3.) What is the name of the formation, in the Frenchmen Mountain, that was formed in the Pennsylvanian Era?
4.) What is the name of the plutonic rocks that were detached from the Wilson Ridge by a low angle fault?
5.) What is the name of the person who drafted these signs?
Please e-mail the answers to these questions to me and do not include them in you log. It would be great (not required) if you were to include a picture of your favorite view from here. (with you in it of course).
Additional Hints
(Decrypt)
Vg vf nyy ba gur fvtaf