The Vernal Pools of Phoenix Park EarthCache
The Vernal Pools of Phoenix Park
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These are the Phoenix Park Vernal Pools. They are located in Phoenix Park in Fair Oaks. There are no dogs allowed in the Vernal Pools, but they can be in the park if they are leashed.
The Phoenix Vernal Pools National Natural Landmark is an example of unique ecosystems that are an important historical component of the central Valley. The highly specialized plants and animals that inhabit this "micro-ecosystem" are what make Vernal Pools so interesting. The plants and animals that inhabit in this environment have evolved to thrive under conditions that vary from extremely wet to completly dry. After the winter rains fill the pools, freshwater crustaceans, amphibians, and invertibrates will emerge. Along with the surge in animal life, the spring also brings the beautiful flowering plants for which vernal pools are famous. Only plants and animals that are adapted to this cycle of wetting and drying can survive in vernal pools over time.
Fall, Winter, Spring
The pools are essentially geologic depressions that are flooded during late fall, winter, and spring. The water collects in these depressions because the underlying soil is am impermiable layer called hardpan. Throughout the wet winter months, vernal pools may collect enough water to fill and empty several times. During the wet season, Insects, Crustaceans, and Plants take advantage of the abundant moisture for reproduction. Creatures that inhabit the pools are perpetuated via the production of cysts and/or eggs, and plants produce seeds that become buried in the muddy pool bottom. The mud protects the cysts, eggs, and seeds from the hot, dry Central Valley Summer.
Summer
By late summer, amphibians have dug deep into soils and have gone dormant awaiting the next rainy season. The vernal Pools have completly dried out and most of the plant and animal species have either disappeared into the soils or set seed and died. In this phase vernal pools are really "banks" full of resting seeds, cysts, and eggs that can survive through summer, and even extended droughts, until the onset of the rains begin the cycle anew.
Mima Mounds
The small hills interspersed between the pools are called Mima Mounds. Most of the plants found on the mima mounds are introduced weedy plants not originally found in California. Plants grow readily on the mounds because the soil is well cultivated by ??????? and worms. There are many hypotheses of how the mima mounds form. Some scientists believe that ??????? are important in the formation of mima mounds; others believe that ??????? have adapted to the little hills that formed by other means.
The Soil
The nature of the soil is instrumental in determining whether vernal pools will develop. The soil at Phoenix Park belongs to a type called the Redding Series, and is formed from the gravel and cobble filling the eastern Sacramento Valley. These materials have washed down from the weathered Sierra rocks by the American and similar rivers. The surfice soil and upper subsoil are reddish, granular, and pourus. Underlying the upper subsoil is hardpan, which is clay cemented together by siliceous (silicone containing) chemicals. Because the subsoils and hardpan are impervious to water, rainwater will stand in depressions in the soil and cannot percolate down to ground water. Instead, the water evaporates slowly. These water-filled depressions are the vernal pools.
LOGGING REQUIREMENTS...
All info (except #4) is located on the kiosk at the posted coords.
1. Send me an E-Mail and tell me the name of 2 species of Birds, 1 Invertibrate, and 3 Plants that inhabit the vernal pools.
2. Also include the size of the Invertibrate that you choose.
3. What do some scientists believe are important in the formation of Mima Mounds?
4. There are some features in the soil at
N 38 39.128 W 121 13.046. Go to that spot and tell me whether the soil in the pools are fragile or resiliant.
5. Finally, include a picture of yourself with your GPS in front of the Phoenix Park sign right near the kiosk. (not required, but appreciated)
Any logs without the required E-Mail being sent will be deleted.
A special thanks to TerryDad2 for his help.
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