Stratigraphy The study of the origin, relationship and extent of rock layers (Strata).

Lithostratigraphy Each layer is a different rock type. Chronostratigraphy Each layer is a different age. Biostratigraphy Each layer contains a different fossil assemblage.

Lithostratigraphic Units Supergroup Group A Formation A Member A Member B Member C Formation B Member D Member E Member F Formation C Member G Member H Group B Formation D Member I Member J Member K Member L Member M Formation E Member N Member O Member P Member Q Formation F Member R Member S Member T Supergroup | Group | Formation | Member | Bed

Lithostratigraphic Example: Grand Canyon

How do we Illustrate Stratigraphy? Stratigraphic Columns Cross Sections Geologic Maps

Stratigraphic Column: John Day Fossil Beds NM

Geologic Maps Snoqualmie Pass

Chronostratigraphic Map of Washington

Cross Sections

Principles (Laws) of Stratigraphy Principle of… Original Horizontality Superposition Lateral Continuity Cross Cutting Relationships Inclusions Faunal Succession Walther’s Law

Nicholas Steno

1. Principle of Original Horizontality

2. Principle of Superposition Youngest Strata Oldest Strata

3. Principle of Lateral Continuity

Lateral Continuity

Charles Lyell

4. Principle of Cross Cutting Relationships

5. Principle of Inclusions

6. Principle of Faunal Succession Sketch by Baron Cuvier ( )

William “Strata” Smith

6. Principle of Faunal Succession "... each stratum contained organized fossils peculiar to itself, and might, in cases otherwise doubtful, be recognized and discriminated from others like it, but in a different part of the series, by examination of them."

Biostratigraphy Defined by first and last appearance of index fossils and/or fossil assemblages Superzone - Biozones - Subzones

Diatoms

Boundaries: Conformable Bed Contacts GradationalSharp

Boundaries: Unconformities Gaps in Rock = Gaps in Time

Types of Unconformities: Nonconformity

Nonconformity - Grand Canyon

Using Inclusions to Recognize a Nonconformity

Types of Unconformities: Angular Unconformity

Formation of an Angular Unconformity

Angular Unconformity in the Grand Canyon

The Angular Unconformity at Siccar Point, Scotland Source: Edward A. Hay, De Anza College, Cupertino, CA

Types of Unconformities: Disconformity

Formation of a Disconformity

Walther’s Law Johannes Walther ( )

Concept of Sedimentary Facies Sedimentary Facies refers to all of the characteristics of a particular rock unit. The characteristics of the rock unit come from the depositional environment. Facies Depositional Environments

Facies Example A = Sandstone facies (beach environment) B = Shale facies (offshore marine environment) C = Limestone facies (far from sources of terrigenous input) Facies Change

Marine Transgression = Sea Level Rise Marine Regression = Sea Level Fall

Walther’s Law Sedimentary environments that started out side-by-side will end up overlapping one another over time due to transgressions and regressions. Limestone Shale Siltstone Sandstone Reef Lagoon Near Shore Beach Environment Facies

Marine Trangression Walther’s Law

Marine Regression

“The sea goes in, the sea goes out.”

Blue = No deposition

Vail Curve of Sea Level History TransgressionRegression

Correlation

ABC Regression Transgression

Example of Correlation

Colorado Plateau Correlation

Chronostratigraphic Units Chronostratigraphic (Time-Rock) Unit Eonothem Erathem System Series Stage

Chronostratigraphy and the Development of the Geologic Time Scale

Chronostratigraphic & Time Units Time Unit Eon Era Period Epoch Age Time-Rock Unit Eonothem Erathem System Series Stage

Geologic Time Scale

Relative Dating of Rocks Using Stratigraphic Principles

Example 2 of Relative Time