Ancient environments
Central Kansas - 80 Ma
Setting the Stage: Major Erosional/Depositional ‘Provinces’
Understanding the distant past by reconstructing:
• Ancient environments• Ancient climates• Ancient life• Ancient ecosystems
“The present is the key to the past.”“The past is the key to the present.”
Ancient Environments Paleoenvironment
A past environment (i.e., meandering stream, delta, ocean basin) that existed in a given area.
Determined through the study of:
• modern depositional systems
• rocks & enclosing structures
• biological remains (fossils)
PaleoenvironmentPresent-Day environments ?
Yazoo River
Aerial view Cross section
PaleoenvironmentPresent-Day environments ?
Mississippi Delta
Aerial view Cross section
PaleoenvironmentPresent-Day environments ?
Outer Banks
Aerial view Cross section
Clues Within the Sediment I
Minerals?
Grain size?
Grain sphericity?
Grain sorting?
Matrix?
Clues Within the Sediment II
Planar Bedding
Cross Bedding
Imbrication
Graded Bedding
Cut and Fill
Ripple Bedding
Which way did the current flow?
Graded Bedding in a modern stream deposit
Ancient Stream Deposit
PaleoenvironmentThe Geological record
Paleozoic deltaic deposits in Tennessee
PaleoenvironmentThe Geological record
Paleozoic meandering stream deposits in Pennsylvania
PaleoenvironmentThe Geological record
Eocene barrier island deposits in South Carolina
PaleoenvironmentThe Biological Record
Wright whale
40 Ma whale skeleton, Egypt
Ancient ClimatesPaleoclimate
Determined through the study of:
• modern climate
• rocks & associated structures/fossils
• chemistry
Temperature, humidity, rainfall, etc. in a given area during a particular ancient time interval.
ClimatePresent-Day Climates?
Alpine/Polar (glaciers)
Desert (dune fields)
PaleoclimateThe Geological Record
Desert (aeolean sandstone)
Alpine/Polar (morraines)
PaleoclimateThe Biological Record
woolly mammoth
trees & other plants
Paleoclimate Chemical records
foraminifera
Ice cores
Scallops & other mollusks
Temperature Fluctuation Based on O-18 analyses
Chemical records – oxygen 18
Sea Level Fluctuation Based on O-18 analyses
North America during last glacial maximum ~ 21 Ka
During the:
Ord = Ordovician
P/T = Permo-Triassic
Cretac = Cretaceous
PETM = Paleocene-Eocene Thermal Maximum
LGM – Last Glacial Maximum
LIA - Little Ice Age
Paleogeographic map & Paleotemperature distributions
Ancient LifePaleontology
Life that existed during a particular time interval in the distant past.
Understanding gained through the:
• examination of preserved remains (fossils)
• comparison to living organisms
PaleontologyTypes of Fossils
Body Fossils
Molds & CastsCarbon Films
PaleontologyPresent-Day Equivalents?
Tiger skull
Scallop
dragonfly
Ancient EcologiesPaleoecology
Interactions among living organisms living within a particular ancient environment.
Understanding gained through the:
• study of modern ecologies
• examination of fossils
Ecology
Great Barrier Reef, Australia
Reconstructing Paleoecology
Niobrara Formation (85 Ma), Kansas
Study Rock Exposures
Reconstructing Paleoecology
Niobrara Sea (85 Ma), North America
Determine Depositional Environment
Reconstructing PaleoecologyCollect and Study Fossils
Plesiosaur
Ammonite
Mosasaur
Niobrara Sea (85 Ma), Kansas
Paleobiology
“Fish-within-a-fish” – Niobrara Formation (85 Ma), Kansas
Study of the mode of life of organisms (i.e., how big an animal grew, how it moved, what it ate)
Paleobiology
Pierre Sea (72 Ma), South Dakota
Paleobiology
Pierre Sea (72 Ma), South Dakota
Paleobiology/Paleoecology
Baby mammoth – permafrost (40 Ka), Siberia, Russian Federation