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