What is recorded here?
Morgan extended transform-boundary geometry to rigid spherical blocks, estimated relative poles and half-spreading rates in several ocean regions, and examined motion-circuit closure with stated uncertainties. A curved fault trace and a varying spreading speed can be two signatures of the same rotation. Morgan treated a plate pair as a relative rotation with three parameters: the pole latitude, pole longitude and angular speed. Fault directions constrained the pole, while magnetic anomaly spacing constrained the rate. He compared this construction with Atlantic, Pacific–North American and Pacific–Antarctic observations, then estimated an unmeasured pair from a circuit of relative angular velocities. The analysis distinguished present motion from the average motion since continents separated. It also exposed weaknesses: inferred strikes, excluded fault segments, magnetic time-scale choices, uncertain local boundaries and deformation within nominally rigid blocks. The result is a concrete framework and set of historical tests, rather than a validated modern map of every plate. The shared spherical idea in contemporaneous McKenzie–Parker work and the underlying measurements retain separate credit.
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Scientific scope
The kinematic model treats stated crustal blocks as rigid motions on a sphere with relative rotation poles. Its fit and inferred boundaries do not prove a complete dynamical cause of plate motion. Deformation, uncertain observations and changing geometry limit the idealization. Parallel McKenzie–Parker work and later global plate models remain separate.
Read the original work
- W. Jason Morgan, Rises, Trenches, Great Faults, and Crustal Blocks, original JGR paper, Harvard copy
- AGU Crossref deposit for Morgan1968 rigid crustal-block paper
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People and systems
W. Jason Morgan
Source-listed contributors to this scoped work. Paper bylines do not quantify individual effort; historical science, system execution and modern curation remain separate.
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English catalogue narrative
Morgan: spherical block motions tested against faults and spreading rates
Morgan extended transform-boundary geometry to rigid spherical blocks, estimated relative poles and half-spreading rates in several ocean regions, and examined motion-circuit closure with stated uncertainties.
A curved fault trace and a varying spreading speed can be two signatures of the same rotation. Morgan treated a plate pair as a relative rotation with three parameters: the pole latitude, pole longitude and angular speed. Fault directions constrained the pole, while magnetic anomaly spacing constrained the rate. He compared this construction with Atlantic, Pacific–North American and Pacific–Antarctic observations, then estimated an unmeasured pair from a circuit of relative angular velocities. The analysis distinguished present motion from the average motion since continents separated. It also exposed weaknesses: inferred strikes, excluded fault segments, magnetic time-scale choices, uncertain local boundaries and deformation within nominally rigid blocks. The result is a concrete framework and set of historical tests, rather than a validated modern map of every plate. The shared spherical idea in contemporaneous McKenzie–Parker work and the underlying measurements retain separate credit.
Scientific scope
The kinematic model treats stated crustal blocks as rigid motions on a sphere with relative rotation poles. Its fit and inferred boundaries do not prove a complete dynamical cause of plate motion. Deformation, uncertain observations and changing geometry limit the idealization. Parallel McKenzie–Parker work and later global plate models remain separate.
People and systems
W. Jason Morgan