EarthCache

Transverse Range View Earthcache

A cache by PathfinderMark Send Message to Owner Message this owner
Hidden : 1/12/2010
In California, United States
Difficulty:
1 out of 5
Terrain:
1 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:

As an earthcache, there is no “box” or “container” to discover. Rather, with this cache, you discover something about the geology of the area. For more info, consult www.earthcache.org.

This cache is handicap accessible.

This earthcache is located just moments from two major Interstate exits in a busy shopping center area.

The transverse ranges are very unusual in that they run east to west. From east to west the transverse range includes the San Bernadino mountains, the San Gabriel mountains (the mountains you are looking at here at this GZ) and the Santa Monica Mountains. The orientation of the transverse range was created as the Pacific Plate slowly rotated counterclockwise. This rotation not only created the numerous faults and earthquakes for which the area is famous, but it also created the transverse ranges themselves. These mountains are fault block mountains formed during periods of subduction. A dip-slip motion has resulted in the uplift of these mountains. Most of this uplift has taken place relatively recently in geologic time.

Cucamonga Peak
Cucamonga Peak is one of the highest peaks in the San Gabriel Mountains of California. The area is in the Cucamonga Wilderness on the San Bernardino National Forest. Named for Tiburcio Tapia's Rancho Cucamonga, the mountain towers over the present-day cities of Rancho Cucamonga, Ontario, and Fontana. This is the main peak visible from I-15 (Cajon Pass) and from I-10 as it goes through Cucamonga and Ontario.

The Transverse Ranges:
The Transverse Ranges are actually a set of three mountain chains that were formed by a series of complex of tectonic forces because of the interaction of the Pacific Plate and the North American Plate along the San Andreas Fault system. However, unlike the majority of mountains that are related to the San Andreas fault system, their orientation is along an east-west axis. This is because of a complex geological “bend” that the San Andreas Fault takes as it goes from being a fault in the middle of the “big valley” to a coastal fault enroute to San Francisco. But that huge bend is the reason these mountains were formed -- The crust atop the Pacific Plate south of the ranges does not easily make the turn westward as the entire plate moves northwestward, forcing pieces of the crust to compress and lift. That means that the mountains continue to “grow upward” as the Pacific Plate continues to shove northward on this east-west piece of the fault before it slides around to the west.

The crust which comprises the Transverse Ranges is part of what is known as the Salinian Block. The mountain range you see is composed of rocks that have been stacked here but that have traveled from northwestern Mexico. Basically, part of the North American Plate was broken off from northwestern Mexico as the Gulf of California rifted open.

You will notice that the rock color and visual composition, even at this distance varies somewhat. Sedimentation and tilt (fault) factors are both present in front of you. Furthermore, the southern facing slope is exposed to the sun during most day light hours, leading to one of the driest mountainside exposures in this part of the state. As a result very few plants grow on these slopes, and those that do are rich in creosote (and thus BURN easily – locals remember many a fire on these slopes). Because few plants grow on the lower slopes, the area erodes easily, sending the sedimentary soil cascading down the hillside. This sedimentation comes from soil that was originally part of the alluvium of three major rivers that has been uplifted over time (see above description).

Congrads to 5150Joker for FTF (First to Finish logging requirements)

Logging Requirements:
Send the answers to #1-#3 to me through my geocaching profile.

1.List the name “GC22YEO Transverse Range Earthcache” in the first line of your email. Also, list the number of people in your group.
2.Based on the information above, describe what two forces have geologically affected the mountain range to your north in the greatest way.
3.Describe the rock color and apparent deposition changes in the upper and lower part of Mount Cucamonga. Describe WHY there are the different colors (see above description).
4. (Per current gc.com guidelines, photos are no longer allowed to be required. HOWEVER they are encouraged, since they can help clarify that you have visited the location if your other logging requirement answers are vague). Post a picture of yourself and your GPS with your log that shows You, the GPS and the mountain range OR outdoors business nearby.

I will only respond if you have incomplete logging requirements. Go ahead and log your cache

Resources:
Urban Partnership.org (visit link)
Wikipedia “Transverse Ranges” (visit link)
Wikipedia “Cucamonga Peak”

Additional Hints (No hints available.)

 

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205 Logged Visits

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Current Time:
Last Updated: on 3/22/2017 10:54:56 AM Pacific Daylight Time (5:54 PM GMT)
Rendered From:Unknown
Coordinates are in the WGS84 datum