Cratonic sequence

A cratonic sequence is a large-scale succession of sedimentary rocks deposited across a craton during a cycle of sea-level rise and fall, bounded by major unconformities.

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Marine transgression: The landward migration of a shoreline as relative sea level rises. Rising seas spread marine deposits across the craton during the sequence’s transgressive phase.
Craton: An old, stable part of continental lithosphere that has undergone little deformation over long periods. The craton provides the broad, relatively stable platform across which the deposits spread.
Sauk sequence: A lower Paleozoic cratonic sequence that records widespread marine flooding across Laurentia. It is the earliest of the classic North American cratonic sequences.
John Wesley Powell: An American geologist and explorer who investigated the geology of the Colorado Plateau and western North America. Powell’s work helped establish the importance of major unconformities in interpreting continental history.
Marine regression: The seaward migration of a shoreline as relative sea level falls or sediment fills a basin. Shoreline retreat marks the regressive phase that follows widespread marine flooding.
Stratigraphy: The study of rock layers, their relationships, and their chronological order. Cratonic sequences are stratigraphic units defined by their position between regional surfaces.
Tippecanoe sequence: A Middle Ordovician to Early Devonian cratonic sequence deposited across Laurentia. Its strata record a major interval of marine coverage between regional unconformities.
Laurentia: The ancient continental landmass that formed the core of North America and parts of Greenland and Scotland. Classic cratonic sequences were defined through their record across Laurentia.
Unconformity: A surface representing erosion or a gap in the geological record. Major unconformities bound cratonic sequences and record pauses or erosion between depositional cycles.
Sequence stratigraphy: The analysis of sedimentary strata in relation to changes in accommodation and sediment supply. This framework interprets the surfaces and depositional patterns that define cratonic sequences.