Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

Termination

Stratal termination type.

Classify a seismic/stratigraphic stratal termination (onlap, downlap, toplap, truncation, concordance) by its contact position and process meaning. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Contact

Which bounding surface carries the termination: basal, top, or either.

Class

Geometric class of the termination.

Interpretation

Process interpretation of the termination.

• Stratal terminations and systems tracts are interpretations sensitive to seismic resolution, datum, compaction, subsidence, sediment supply, chronology, and depositional model. A geometric angle or thickness alone does not identify sequence boundaries.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• Systems Tract Lookup

  Look up the cycle position, base-level trend, and bounding surfaces of a depositional systems tract within a stratigraphic sequence.

• Geologic Time Scale Lookup

  Map an age in millions of years ago (ICS boundaries) to its Phanerozoic plus Ediacaran period, era and boundary ages; boundary ages belong to the younger period.

• Rock Density Lookup

  Look up the typical dry bulk density range in g/cm3 for a common rock type.