Fold (geology) : In structural geology, a fold is a stack of originally planar surfaces, such as sedimentary strata, that are bent or curved during permanent deformation.
Park at the posted coordinates. This is the parking area for the Wheeler Creek trailhead. It can be very busy at times.
This massive Z-fold in the rock layers can be viewed by looking north across the Ogden Canyon from the parking area or from farther up the Wheeler Creek trail. The Z-fold in this formation is far less common to see than other types of folds, especially this massive in size.
Folds were caused by compression when the continential plates were colliding about 100 million years ago during the Cretaceous period. In a fold formation, compression causes the rock layers to bend and fold into many shapes. In a fault formation, compression can cause the rock layers to shear at the fault line and slip up or down from each other.
The rocks in this Z-fold are of the Mississippian geologic period, around 330 million years old and are composed almost entirely in Mississippian formations (mostly limestone): Deseret Limestone, Gardison Limestone, and Humbug Formation.
But this Z-fold is nowhere near that old. Around 230 million years after deposition of these sediments, during the Sevier Orogeny, a compressional event occurred called the Willard Thrust that brought about the shortening, shearing, faulting, and folding of these deeply buried rocks. Enter more geologic time and the entire structure became exposed along the cliffs of Ogden Canyon.
This is the massive Z-fold you are looking for.
View of the Z-fold from higher up the Weeler Creek trail.
Information from Shawn Willsey, College of Southern Idaho and the Weber State University in Ogden.
To log this earthcache, you need to visit this area, then message me the info below.
1- Include the GC code, and all the people you may be submitting answers for.
2- This Z-fold was caused by compression. From what driection/directions was this area compressed ?
3- Do you think the layers of limestone were brittle or pliable when this Z-fold was formed ?
4- Do you think the Z-fold being this close to Pineview Reservoir affects the safety of the reservoir, and why do you think that ?
5- What you think caused the erosion in this area so that we are able to view this magnificent Z-fold ?
6- Post a photo at the location of you and/or a personal item with the Z-fold formation in the background. You have to actually visit this earthcache site. Not including a photo with your log or photoshopping something will get your log deleted.
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