Two diagrams illustrating the shift of sedimentary facies during transgression (creating an ‘onlap’ pattern with the underlying beds) and during regression (creating an ‘offlap’ pattern with the underlying beds).
<a href="//commons.wikimedia.org/wiki/User:Woudloper" title="User:Woudloper">Woudloper</a>
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<span class="int-own-work" lang="en">Own work</span>