My project was to look at the Navajo and Kayenta Formation’s physical and erosional properties and how they contribute to the dramatic landscape of Zion National park. My first stop was at the Zion Narrows which is a canyon carved by the downcutting of the North Fork of the Virgin River. What is of interest is that the area of the narrows where the canyon is made up only of the Navajo Sandstone the canyon is much narrower unlike areas where the underlying Kayenta Fm is being eroded as well. This because the top of the Kayenta is an easily eroded shale and siltstone and cause undercutting of the Navajo above which is a very homogeneous unit and is very strong.
Our second stop was at Weeping rocks where we explained the processes of the Contact Spring which deals directly with the large porosity of the Navajo and the much finer grains of the Kayenta not allowing as much water to move vertically therefore it moves out laterally until it discharges out at the out crop.
The third stop we talked about the formation of blind arches and looked at the Great Arch of Zion. We also looked at some float from the Kayenta Fm. as we were eating lunch here and saw some cool trace fossils in a few samples.
Fourth stop dealt with hoodoos in the Navajo Fm where finer grained cross sets protect the more easily eroded cross sets below them creating pillars of standing rock.
Fifth stop was looking at slot canyons formed by structurally created joint zones in the Navajo Sandstone. In the canyons we saw more excellent example of crossbedding, small boulders jammed into crevices, and potholes forming.
Finally the Sixth stop included the checkerboard mesa whichgot its name from the cross sets being intersected with fractures created by “expanding and contracting” forces due to rapid changes in temperature
Th other highlights for me included a few lifelist birds which included a Winter Wren, American Dippers, and a Stellar’s Jay.
My only regret is the limited time in which we had to enjoy Zion and the fact that we only scrathcehed the surface of Zion’s wonders.