PaleoEverest Lake, Southwestern Side of Franklin Mountain

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Paleo-Everest Lake, South-western Side
ofFranklin Mountain

• Plio-Pleistocene? Lake Formed/
• Preserved By Structural Sagging Along Eastern
  Bolson Border Fault

by Bruce Cornet
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El Paso Geology

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Graben-Horst Structurewith rotation into faults
Structural rotation into faults created
conditions for lakesto form and/or to be
preserved.
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Franklin Mountain Geology

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Lake Bed Outcrop Satellite View
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Hypothetical Reconstruction of Lake
Everest Lake
Lake named after Everest Drive.
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Outcrop No. 1
Lake bed is about 10 feet thick.
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Boulder Conglomeratesabove lake bed
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Turbidite lobes in upper part of section.
Lake bed is about 10 feet thick.
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Turbidite Lobe 1
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Turbidite Lobe 2
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Turbidite Lobe 3
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Turbidite Lobes Occur at Same Level
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2
1
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Close-up Showing Graded Bedding
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Outcrop No. 2
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Lake Bedsweatherfrom blackto grayto brown
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Outcrop No. 3
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Close-up
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Limited Extent of Lake Strata
Outcrop 1
All conglomerate
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Enlargement of Conglomerate Cut
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Conglomerate from Ground Level
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Conglomerate Throughout
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Close-up of Conglomerate Facies
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Conglomerate Facies
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Mudstone-Conglomerate Facies
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Plio-Pleistocene Lake
Pliocene/Pleistocene Formation of Lake in Mesilla
Bolson
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Plio-Pleistocene Lakes
A graben-formed lake also existed next to
the border fault.
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Rio-Grande Flow-through
Pleistocene/Recent Flow through Paso Del Norte
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Outcrop of Everest lake bed
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Close-up of Alternating Dark and Light Layers
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Gypsum veins
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Invertebrate Fossils from Lake Bed
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group of snails
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Distinctive Snail with Ornament
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Juvenile Snail with Ornament
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Ornamented Snail from Bermuda
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Large Clam
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Large Clam
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Large Pectin
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Shieldshrimp
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Shieldshrimp Head (Triops)
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Shieldshrimp Head (Triops)
Snail with soft parts preserved?
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Shieldshrimp Body (Triops)
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Shieldshrimp Body (Triops)
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Shieldshrimp Body(Triops)
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Head and Body
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Shieldshrimp
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Clam-shrimp (Conchostracans)
Any member of the crustacean order Conchostraca
(subclass Branchiopoda), a group of about 200
species inhabiting shallow freshwater lakes,
ponds, and temporary pools throughout the world.
Clam shrimps are so called because their entire
body is contained within a bivalve shell
(carapace) that resembles the shell of a small
mollusk. Inside the shell the trunk of the animal
carries up to 28 pairs of leaflike limbs that
filter microscopic food particles and also assist
in locomotion in those species that swim.
Conchostracans are abundant in the fossil record
dating back to the Silurian Period (438 to 408
mya).
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Layers covered with clam-shrimp
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red-stained conchostracans(clam-shrimp)
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large conchostracans
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large conchostracan
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Ostracods (Crustaceans)

• Ostracods are very numerous in both freshwater
  and marine environments. There are 2000 living
  species. The larger marine species are also known
  as mussel shrimps or seed shrimps, but the
  freshwater ostracods are usually smaller than a
  millimetre.
• There are 10,000 or so fossil species dating
  from the Late Cambrian period (about 500 million
  years ago) to recent times. Their great abundance
  and widespread distribution have made them useful
  index fossils for dating marine sediments,
  notably in oil exploration.

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ostracod layer
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Vertebrate Fossils from Lake Bed
Poorly-preserved fish with disarticulated scales
and bones.
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fish scale
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fish scale
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fish scale and bone
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fish operculum? (gill cover)
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Thick Plant Leaf Fragments (succulent)
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Lower Part of a Plant Leaf (palm frond?)