Geology of Colorado (Boulder Valley) - Field Trip #1, Stop #1: Fountain Formation

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Notice cracks that are NOT on the bedding plane.  These are exfoliation joints caused by weathering and the formation being brought back to the surface.  The rock was under extreme pressure at depth.  As it came up and weathered, these surface layers are popping off perpendicular to the bedding planes.
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Notice cracks that are NOT on the bedding plane. These are exfoliation joints caused by weathering and the formation being brought back to the surface. The rock was under extreme pressure at depth. As it came up and weathered, these surface layers are popping off perpendicular to the bedding planes.