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Field Location: Natural Bridges National Monument and vicinity
(White Canyon) (click on link to see photos).
Geologic Feature: Interfingering of Permian lacustrine or marine and
continental strata at a 1-10 m scale. Interfingering of eolian and mudflat
facies at a 1-100 m scale. Permian/Triassic unconformity; change from
arid (eolian) to wetter conditions (mudflats, fluvial systems, paleosols,
plant fossils, trace fossils).
Necessary Background Information: Permian/Triassic unconformity and
potential causes.
Geologic Problem: How are climate, sea level change, and tectonic
activity reflected in these rocks?
Rock Units Exposed: Permian Cedar Mesa Sandstone, Organ Rock
Formation, and White Rim Sandstone. Triassic Moenkopi and Chinle
Formations.
Skills: Documenting depositional environments. Identifying fossils and
trace fossils.
Other Questions to Consider: (1) What are the differences between
water-deposited and wind-deposited sediments? (2) What timescales are
involved in depositing various thicknesses of materials by different
mechanisms? (3) What magnitude of climate change is necessary to cause such
drastic changes in depositional conditions? (4) What types of creatures lived
in these environments? (5) What characteristics of plants can be linked to
their environments?
Anticipated Outcomes: Differentiation among marine, transitional, and
freshwater environments. Physical description and analysis of fossils.
Ability to “create a story” from field (i.e., restricted sampling) evidence.
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