Tahsin Islam University of Barisal.

Stratigraphy: Stratigraphy is the study of rock layers (strata) and their relationship with each other. Stratigraphy provides simple principles used to interpret geologic events.

Law of Original Horizontality: Sedimentary rock layers are deposited horizontally. If they are tilted, folded, or broken, it happened later.

Law of Superposition : When sedimentary rock layers are deposited, younger layers are on top of older deposits.

Cross-Cutting Relationships Rock that are cut by another geologic feature are older than the feature that cuts them.

Systematic sequence of fossils with time. Extinct fossils do not reappear in younger rocks. Faunal Succession

Principles of Relative Age Law of Lateral Continuity : Sedimentary rock layers extend in all directions horizontally unless a river erodes them or an earthquake moves them

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