Welcome to the OpenGeology.org Historical Geology textbook!

This textbook is intended for undergraduate courses in Earth history. It was written by Callan Bentley, Karen Layou, Russ Kohrs, Shelley Jaye, Matt Affolter, and Brian Ricketts. It is a work in progress.


What is Historical Geology?

A Brief History of Earth

Earth as a System

Earth Materials – The Rock Forming Minerals

Earth Materials – Rocks

Plate Tectonics

Geologic time

Evolution Part I: The Theory

          Taphonomy: The Science of Death and Decay

Innovations of Life Through Time: Life Finds a Way

Mass extinctions
[NEW  as of December 2022]

Stratigraphy – The Pages of Earth’s Past

Using sedimentary structures to interpret ancient environments
[NEW URL AS OF 12/27/2022]



Case studies:

Nebular theory and the formation of the solar system

Earth’s oldest rocks

          Greenstone belts: primordial tectonics

Starting tectonics and making the first continents

Snowball Earth glaciations


Discovering plate tectonics

The Grenville Orogeny & the rifting of Rodinia

Tippecanoe Sequence: A sequence stratigraphic view

The Taconian Orogeny

California’s Coast Ranges: a Mesozoic accretionary wedge complex

The mixed-up quartzites of Cape Agulhas

Palimpsest outcrops

Extremadura: interpreting a geological cross-section

Diversity in the marine fossil record

Reptile radiation

Dinosaur classification

Dino Debates – dinosaur ecological controversies

Western Mesozoic orogenies

San Andreas Fault & the Basin and Range

The Parallel “Roads” of Glen Roy
[NEW  as of November 2022]

The Channeled Scablands of eastern Washington
[NEW  as of November 2022]

The interplay of carbon & oxygen cycles in Earth history
[NEW  as of January 2023]

Quaternary Quandaries: defining the geologic “now” and explorations of the Anthropocene

          Human Evolution

Additional case studies in the works (coming soon):

Big Bang

Crust formation & evolution & differentiation

Moon forming impact

Ocean formation & evolution

Atmosphere formation & evolution, oxygenation

Origin of life

A history of fossil plants

Sauk/early Paleozoic transgression

The Acadian Orogeny

The Alleghanian Orogeny

Large igneous provinces / Flood basalts

Pleistocene “Ice Ages”

Epicontinental seas – Pz, Mz, Cz

Carboniferous coal & natural gas – cyclothems


Tools of the trade:

Earth Materials – Mineral identification

Evolution Part II: Paleontological applications

Sequence stratigraphy

Geologic structures

Geologic maps

Way-up structures

Virtual field experiences (VFEs):

Fossil correlation

Glaciers, glaciated landscapes, and glacial sediments

Glacier National Park, Montana

The Geodetic Hills Fossil Forests: Unraveling a Paleoclimate Puzzle

Massanutten Synclinorium, Virginia

The Moho (crust/mantle boundary)

A Plate Boundary Odyssey

Siccar Point, Scotland

Wind River Canyon, Wyoming

Stromatolite diversity in the Belcher Islands

Modern & ancient microbialites in Western Australia

Corridor H, West Virginia

Virtual sample sets (VSSs):


3D mineral samples, set 1
[NEW  as of January 2023]

Igneous rocks

Igneous supplementary set

Sedimentary rocks

Metamorphic rocks

3D rock samples, set 1

Primary sedimentary structures

Sediment samples

Relative dating

Tectonic structures


Funding for this project was provided by VIVA, the Virginia Library Consortium and the Northern Virginia Community College Presidential Sabbatical Award.

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Please inform us of any feedback or technical issues: cbentley@pvcc.edu