Latah Formation: History and Case Studies
Faculty Mentor
Dr. Lindsay MacKenzie
Presentation Type
Poster
Start Date
May 2025
End Date
May 2025
Location
PUB NCR
Primary Discipline of Presentation
Geosciences
Abstract
The Latah Formation is a series of discontinuous sedimentary interbeds between the flows of the Columbia River Flood Basalts outcropping across northern Idaho and eastern Washington. Ages ranging between the Middle to Upper Miocene, the sediments represent varied fluvio-lacustrine environments. The deposits are predominantly composed of claystones and shales as alternating, laminated couplets, many containing a variety of fossils. Though the sediments may appear similar across localities, they come from different source rocks, ranging from ashes from Yellowstone hotspot to metamorphic rock from nearby hills. These ancient lacustrine and fluvial environments allowed for great preservation of fossils, often in great quantities. Fossils of note include insects with original color, diatoms and palynomorphs, vertebrate fishes, and fungi. But the Latah Formation’s most famous fossils are plant fossils, exhibiting cellular detail and original tissues in many cases. The diversity of the plant fossils present gives a snapshot of what the climate and environment was like during times of quiescence between basaltic flows.
Recommended Citation
Woodworth, Kylee M., "Latah Formation: History and Case Studies" (2025). 2025 Symposium. 30.
https://dc.ewu.edu/srcw_2025/ps_2025/p2_2025/30
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Latah Formation: History and Case Studies
PUB NCR
The Latah Formation is a series of discontinuous sedimentary interbeds between the flows of the Columbia River Flood Basalts outcropping across northern Idaho and eastern Washington. Ages ranging between the Middle to Upper Miocene, the sediments represent varied fluvio-lacustrine environments. The deposits are predominantly composed of claystones and shales as alternating, laminated couplets, many containing a variety of fossils. Though the sediments may appear similar across localities, they come from different source rocks, ranging from ashes from Yellowstone hotspot to metamorphic rock from nearby hills. These ancient lacustrine and fluvial environments allowed for great preservation of fossils, often in great quantities. Fossils of note include insects with original color, diatoms and palynomorphs, vertebrate fishes, and fungi. But the Latah Formation’s most famous fossils are plant fossils, exhibiting cellular detail and original tissues in many cases. The diversity of the plant fossils present gives a snapshot of what the climate and environment was like during times of quiescence between basaltic flows.
