Answers are grounded in this paper and cite their sources.
In sediments west of the East Pacific Rise between the equator and 20 degrees N, Eocene microfossils are recorded no farther east than 134 degrees W; Oligocene, no farther east than 125 degrees W; while Miocene and Pliocene occurrences extend closer to the crest of the rise. This distribution may result from post-Eocene spreading of the sea floor here averaging about 8 centimeters per year.
No takes yet. Share an insight, caveat, or question.
W.R. Riedel (1967) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: