Stratigraphy: Historical Geology Dr. Prabha Joshi Department: B.E. Civil Engineering Subject: Engineering Geology Semester: III Teaching Aids Service by KRRC Information Section Teaching Aids Service by KRRC Information Section

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

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

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

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 Rock unit Supergroup | Group Formation Member Bed

Lithostratigraphic Example: Grand Canyon

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

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

1. Principle of Original Horizontality

2. Principle of Superposition Youngest Strata Oldest Strata

3. Principle of Lateral Continuity

Lateral Continuity

4. Principle of Cross Cutting Relationships

5. Principle of Inclusions

Using Inclusions to Recognize a Nonconformity

6. Principle of Faunal Succession Sketch by Baron Cuvier (1769-1832)

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

Boundaries: Conformable Bed Contacts Gradational Sharp

Boundaries: Unconformities Gaps in Rock = Gaps in Time

Walther’s Law Johannes Walther (1860-1937)

Concept of Sedimentary Facies Depositional Environments 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.

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. Facies Limestone Shale Siltstone Sandstone Reef Lagoon Near Shore Beach Environment

Marine Trangression Walther’s Law

Marine Regression

“The sea goes in, the sea goes out.”

A B C Regression Transgression

Correlation

Example of Correlation

Colorado Plateau Correlation

Colorado Plateau Correlation

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

Chronostratigraphy and the Development of the Geologic Time Scale

Geological Time Scale

Relative Dating of Rocks Using Stratigraphic Principles

PHYSIOGRAPHIC DIVISIONS The Himalayan Mountains (ii) The Indogangetic Plains (iii) The Peninsular Plateau