Yuma West Wetlands is one of several wetlands that are part of the Colorado River Watershed. Wetlands mark a transitional environment for the flow of water (discharge) and the transport of sediments (erosion). Note erosion and weathering are not the same thing, despite a common misconception. Erosion describes the transport of sediments while weathering is the act of breaking larger rocks into smaller pieces.
Wetlands typically form under certain geologic conditions and have the following qualities:
1) flat land with little topographic and geomorphological differences along local distances
2) stream gradients (elevation change) near their terminus in the wetland shall be low so that the discharge is also low
3) silt and clay sized particles settle out, with sand sized particles only settling during seldom high discharge events
4) little to no difference between high and low tides
5) Flow is not stagnate and is continuous to prevent salt water infiltration
Since modern times, the Colorado River has lost much of its natural wetlands due to dams and extreme water usage. So it is important to preserve and protect them as well as educate to the public about their importance. Wetlands are important geologically speaking in that they filter out sediments before flowing into the ocean (in this case the Gulf of California before the Pacific).
Wetlands are an important driver in the nitrogen and carbon cycles, helping to lock and store nutrients in the rock record. Aditionally, wetlands contribute to nearly 70% of global atmospheric methane emissions. They allow runoff and nutrients to naturally filter through before entering the ocean. This does effect what types of sediments can be deposited. In more recent times, they help filter out polutants. As sand sized particles are not able to pass through the wetlands, the rock record of a wetland would show silt and clay deposits interbedded with organic material (coal) millions of years later.
Why are there wetlands here?
Wetlands exist along this part of the Colorado because the river is near its terminus at the Gulf of California (an inland sea of the Pacific Ocean). This slows down the velocity of the river as the gradient gradually gets closer to 0 feet above sea level. Slowing the river velocity down has consequences including sediment deposition, which brings fertile nutrients to the banks of the river. This allows plants to grow which, through their root systems, can filter finer particles as they travel down the Colorado.
Yuma has 2 wetlands (east and west). The east wetlands is much larger, but more remote to access. It is about 500 acres of wetlands owned by the City of Yuma, the Quechan Indian Tribe, and Arizona Game and Fish Department. The west wetlands (adjacent to West Wetlands Park) is much smaller, and was formerly the city landfill. It consists of 28 acres of wetlands.
Works Cited
https://abbottmarshlands.org/wildlife-plants-and-habitats-2/geology/
https://www.pinterest.com/pin/477874210441524668/
https://serc.carleton.edu/mel/teaching_resources/wetlands_mel.html
https://www.usgs.gov/media/images/colorado-river-basin-map
https://www.americansouthwest.net/arizona/yuma-crossing/national-heritage-area.html
TO LOG A FIND ON THIS CACHE YOU MUST ANSWER ALL THE QUESTIONS BELOW. YOU CAN CONTACT ME THROUGH MY EMAIL OR THE GEOCACHING MESSAGE CENTER TO SEND YOUR ANSWERS. ANY INCORRECT ANSWERS MAY RESULT IN A CLARIFICATION RESPONSE FROM ME.
Note: You will only receive an email from me if I need clarification on your answers. You are free to log the cache as a find whenever you like.
1. "Yuma West Wetlands" on the first line of your email AND list all geocaching names of your party so I can match your answers to them. If you all want to learn something, I would prefer each cacher send me individual emails in the spirt of earthcaching.
2. Take a photo of you (or your signature item if you don't want to show your face) with the Colorado River and surrounding wetlands at the posted coordinates. This photo MUST be attached to your "found it" log at the time of when you submit your log. Please do not send any photos through the message center as Groundspeak compresses images. Each log MUST have a unique and different photo. No two logs may contain the same photo.
3. Look at the shoreline on the Arizona side of the river. Is the shoreline made of sand, silt, or clay or a combination of these? Can you see an abrupt shoreline or is it more gradual and submerged underwater? Explain your observations.
4. Look at the shoreline on the California side of the river. Is the shoreline made of sand, silt, or clay or a combination of these? Can you see an abrupt shoreline or is it more gradual and submerged underwater? Explain your observations.
5. Is the water clear or murky? What may this suggest about the natural filtration that occurs in wetlands? Is filtration here adequate, or are particles getting making it down river?
6. How does the water velocity change as you move towards the center of the river? Does it slow down, or speed up? Explain why this might happen in a wetland environment.
7. Based on the list of geologic conditions that lead to the formation of wetlands (see cache description), name at least 2 that are easily visable.
8. Based on your answers to 7, explain why wetlands naturally formed here along the Colorado and not elsewhere up or down river.