Check Out The Pan, Man!
In Arizona, United States
How Geocaching Works
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For this earthcache, you are going to learn about solution pans.
Solution pans are small scale geological solution features. "Solution", in geology-speak, means that the feature was formed by water and acids dissolving the rock. Pans are typically small, relatively speaking. They are shallow and panlike, and range in diameter from just a few feet to dozens of feet. Pans have an impervious base and hold water.
When dissolution results in larger features, other terms are used for those features, such as pits, cavities, hollows, and even sinkholes, or dolines. A large amount of dissolution in a particular area can ultimately evolve to a subterranean drainage system of drips, trickles, and streams. Under these coniditions, cavities and voids continue to enlarge and rock is undermined. Some blocks of rock are so undermined that they collapse to form isolated holes, coalesced holes, and long sinuous troughs or valleys conforming to underground streams. The resulting landscape is called karst topography.
Solution features like pans are frequently found in the desert, however the features are not formed under arid conditions. Their formation requires the presence of slightly acidic water (rainwater and snow melt usually with carbonic acid) to dissolve a slightly soluble material, usually limestone.
There are many factors that affect the rate of dissolution. These include the composition of the rock, the temperature, and the acidity of the water. Other factors include the type of bedding present, the structure of the rock formations, the extent of fracturing, etc.
In desert landscapes, solution features usually are relicts from an earlier time and a different climate. Wherever calcium carbonate is part of the rock, such as limestone, limy conglomerate, etc., some solution can take place where water is episodically present. Dolomitic limestone, which contains magnesium, is the least soluble of the rocks. Solution features can also be found in gypsum.
Please be careful. Solution pans hold rain water and snow melt. Therefore, they provide a critical source of water for inhabitants of the desert. Whenever you are in the proximity of solution features, be very careful to not contaminate or pollute the water contained inside.
How To Complete This Earthcache:
Bring a tape measure!
The posted coordinates lead you to a spot in the Santa Catalina mountains, where you will find good examples of solution pans. To get there, you need to take the Catalina Highway, which is a paved mountain road that runs north out of Tucson. There is a small fee ($5 or so) for recreational use. You completing an earthcache is recreational use.
At mile 14, you will reach the Windy Point scenic overlook. Plenty of parking is available. After you park, start walking toward the posted coordinates. You will find a trail that ultimately takes you alongside the formations.
When you reach the coordinates, you will find many examples of well formed solution pans in the rock. Click here and here to see examples of what you will see.
The elevation here is around 6500 feet I believe. The scenery is outstanding.
Have Fun! Post A Photo Of Yourself. Sometimes, things become misguided. Earthcaches and geocaches are supposed to be all about the fun and the experience of the location, and about performing simple tasks and getting into the spirit of the earthcache. Try to embrace the original spirit of this earthcache and use one of the most powerful tools available to the field scientist - the camera. Try to take a photo of yourself with one of the solution pans appearing in the background, and post it with your find log. A photo used to be listed as a requirement for this earthcache (prior to 15 May 2011), and as the past logs show, it was fully supported without any protest or controversy. It is a simple task that has always been completely reasonable, with everyone being supportive of it. However today, a photo is not required, due to the poor administrative practice of levying control over a small benign detail that affects nothing outside of the individual earthcache.
For this earthcache, a photo is simply requested, and is in line with the spirit of this earthcache. Click here to see a photo example. I don't care about your GPSr being in the picture.
In order to claim this earthcache as a find, you must complete the following tasks.
Requirement #1 - Make Some Measurements: At the coordinates, you will find a number of well formed solution pans. There are a couple of very nicely formed pans located close to the edge (toward the dropoff). Click here to see one of the pans that I am talking about. With your tape measure, measure the width of one of those solution pans at its widest point. Hint: your measurement should be greater than than 24 inches and less than 144 inches.
Requirement #2 - Identify The Type Of Rock And The Reactive Component: Inspect the rock here and identify it. Is it limestone? Is it sandstone? Is it conglomerate? One of the components of the rock here is reactive to acidic water, supporting the process of dissolution. What is it? Dolomite? Formaldehyde? Magnesium? Calcium carbonate? Gypsum? Calcium sulphate dihydrate? Answering these questions will require you to closely inspect the rock, and perhaps perform a little research.
Requirement #3 - Email: Send an email to me that documents your findings. The email should include your measurement, along with the identification of the type of rock and the reactive component of the rock. Do not post your answers in your on-line log.
Logs not accompanied by email within a reasonable amount of time will be deleted per earthcache rules. Please be careful to get done what you need to get done.
Remember Your Requirements:
Identify Type Of Rock And Reactive Component, and
Send Your Answers In Email.
And If You Will, Please Post A Photo With Your Log.
I hope you have fun.
(No hints available.)
Last Updated: on 4/10/2015 8:22:58 PM Pacific Daylight Time (3:22 AM GMT)
Coordinates are in the WGS84 datum