Some of the best examples of Idaho’s marine Paleozoic fossils are
found near the summits of mountain peaks, elevation 10000′ and higher.
Although they appear in carbonate formations throughout east central
and southeastern Idaho, the core zone is in the southern Lemhi and Lost
River Ranges. Specifically, the best preserved fossils are found in the
Scott Peak Formation, of Mississippian age. 330 million years ago this
part of Idaho was a shallow sub tropical sea far to the southeast, part
of the supercontinent Gondwanaland.
It was not an easy journey to the present for these coral reef relics.
Only those that were quickly buried in lime muds and survived being
eaten, baked, burned, squashed, or torn asunder have survived. No soft
body parts remain, and what we see is not the original shelly part.
This has been chemically replaced by silicates and iron oxides. Fossils
allow us to see and touch the incredibly distant past. This
visualization can also be enhanced by the sense of smell. Crack open a
piece of black fossiliferous limestone. The sulfur dioxide (rotten egg)
smell is another remnant of the decayed organism.
The following 3 photos each depict a pioneer Idaho geologist and a
suite of fossils he likely found in the course of his fieldwork.
JOSEPH B. UMPLEBY (1883-1967) Dressed in his “survey tans” US
Geologist JB Umpleby is ready to leave camp on his mount for another
day in the field, somewhere in Lemhi or Custer County, ca 1912. Colony
coral is found on the summit of Umpleby Peak el 10713′. Fossils
clockwise from lower left: Foraminifer; Bryozoan mass; next 5- colony
coral (Tabulata); next 3- Crinoid (sea lilly) showing head, stem
length, and star shaped axial cross section of stem; spicule.
CLYDE P. ROSS (1891-1965) A prolific writer of Idaho geology, 1947
was a banner year for US Geologist CP Ross with his publication of
“Geology of the Borah Peak Quadrangle”, and “Geologic Map of Idaho”.
Here he is pictured in Sawmill Canyon, Lost River Range, with White Cap
Peak in background, early 1930’s. The bony fish was found enroute to
Clyde Ross Peak el 11724′. Fossils clockwise from bottom center:
Streptelasma; Gastropod; 2 Trilobites; bony fish; 2 Archemedes-fan and
stem mass, Coquina(limestone biomass).
OSCAR K. HUH (1935- ) OK Huh did his Penn State doctoral field work in
the Lemhi Range, shown here in the Diamond Peak area, 1959. Huh
specialized in the Mississippian limestones and defined 4 new geologic
formations, including the Scott Peak. You guessed it, Horn Coral
fossils are found around Huhs Horn el 11292′.
clockwise from lower left: 2 Productids, Orbiculoidia (with original
blue sheen?), Spirifera-these are all Brachiopods; 6 Horn Corals
(Rugosa) of various sizes, 2 show in tact septa. Horn Coral disappeared
with the Permian Extinction, but as members of the Coelenterate family
they are survived today by the jellyfish. Pelecepods (clams).
All material is from the Rick Baugher collection, 4/21/07.
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