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The concrete marker on the west edge of this pulloff claims that this is the Continental Divide. But is it? This cache will teach you about continental divides and require you to determine the truth behind this marker.
You will need to bring a bottle of water with you, and you will need to do some quick map research either before, during, or after your visit -- you may use the sources linked below or do your own map research.
There is no physical cache container to find; to log this earthcache, you will need to email or message us the answers to the questions below. The questions are repeated in the unencrypted hint for your convenience. Remember, you will need water for this cache - or for best results, visit when it's raining.
****************** BRING WATER!! PHOTO REQUIRED!! ******************
HYDROLOGICAL DIVIDES
Hydrological divides, or drainage divides, are lines that separate different drainage basins. A drainage basin is an area in which all water eventually converges to a single point, usually a river mouth. In hilly areas, like around Bisbee, drainage divides are easily identified, as they usually follow ridge lines. In flatter areas, such as the Great Plains, a drainage divide might be a very subtle elevation change and, thus, harder to discern.
There are three different types of hydrological divides: continental divides, major drainage divides, and minor drainage divides. There is another type of watershed relevant to the discussion: endorheic basins.
CONTINENTAL DIVIDES
A continental divide is an imaginary line that separates the waters flowing to the oceans, seas, or coastlines on different sides of the continent. Although the marker here, as in other locations in the western United State, simply reads "CONTINENTAL DIVIDE," North America actually has more than one continental divide. The longest and most prominent is known as the Continental Divide of the Americas, or the Great Divide. It stretches from Tierra del Fuego, at the southern tip of Argentina in South America, and runs up the spine of the Andes, up through Central America, and then runs along the spine of the Rocky Mountains all the way to Cape Prince of Wales, Alaska. Depending on who you ask, however, there are up to four others: the Arctic Divide, St. Lawrence Seaway Divide, Northern Divide, and Eastern Continental Divide.
Two drainage basins separated by the Great Divide are the Colorado, which empties into the Sea of Cortez, and the Mississippi, which empties into the Gulf of Mexico.
MAJOR DRAINAGE DIVIDES
In major drainage divides, water on opposite sides of the divide flow into different drainage basins that do not connect; however, both basins empty out into the same body of water. For example, the Mississippi River and Chattahoochee River have separate river basins, but both empty out into the Gulf of Mexico and, eventually, the Atlantic Ocean.
MINOR DRAINAGE DIVIDES
In minor drainage divides, waters may flow into different drainage basins, but eventually they reconnect before flowing into an ocean, sea, or gulf. For example, the Mississippi and Missouri Rivers have separate and distinct drainage basins at first, but the two rivers eventually meet just north of Saint Louis, Missouri.
ENDORHEIC BASINS
Sometimes water doesn't flow to an ocean at all, but into a closed-off area called an endorheic basin. This generally occurs in more arid regions, where there is not enough rainfall to create significant streamflow, which would cause weathering to the point that water could escape the basin and flow to an ocean. Because the water cannot escape, it tends to build up more salinity over time, becoming brackish or even salty. Some examples are the Great Salt Lake in Utah, Death Valley in California, Crater Lake in Oregon, and even the Wilcox Playa, just north of this earthcache here in Cochise County.
(There is a divide between the northern and southern parts of Sulphur Springs Valley, however, so water flowing from Mule Pass does not flow into Wilcox Playa.)
EVALUATING THE "BISBEE CONTINENTAL DIVIDE"
To log this earthcache, send us a message with the answer to the questions below, or send us an email through the link in our profile, copying and pasting the questions below with your answers. There is no need to wait for a response before logging your find.
1. The name of this earthcache: Bisbee's Continental Divide? (If you're sending a message, this is done for you.)
2. Field task: At the coordinates, pour out some water onto the asphalt in a line from east to west. Does the water flow east? west? both? neither?
3. Photo task: As you're pouring the water out for task #2, take a picture. You can be in it, or not, up to you. If you didn't see this task until you already poured out your water, quick, take a picture of the puddle!
4. Map task: Into what body of water would water flowing west from Mule Pass eventually flow?
5. Map task: Into what body of water would water flowing east from Mule Pass eventually flow?
6. Apply the science lesson: Based on the reading above and your answers to #3 and #4, what kind of hydrological divide is this? Was the marker right?
Apart from the required logging task, other pictures of your visit are always welcome!
SOURCES
Mark A. Gonzalez, "Continental Divides in North Dakota and North America." North Dakota Geological Survey Newsletter, Summer 2003 (Vol. 30, No. 1).
Prof. Eric Clausen, "Mississippi River-Missouri River drainage divide area landform origins in St Charles County, Missouri, USA." Geomorphology Research.
University of Arizona College of Agriculture and Life Sciences, "Arizona Watershed Information."
US Environmental Protection Agency. "Surf Your Watershed - Arizona."
Wikipedia
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