title: Southern hemisphere origin of the cretaceous laytonville limestone of california.
abstract: New paleomagnetic, paleontologic, and stratigraphic data from outcrops of the Laytonville Limestone (101 to 88 million years old) support a Southern Hemisphere origin. A paleomagnetic megaconglomerate test is statistically significant and suggests magnetization at 14 degrees +/- 5 degrees south, predating Late Cretaceous to Eocene (70 to 50 million years ago) accretion. Rapid Kula plate movement or the existence and demise of a now vanished oceanic plate (or both) are required to accommodate the greater than 50 degrees of poleward displacement implied by the paleomagnetic data. This rapid motion brings into question the validity of a "speed limit" for absolute plate velocity based on present-day plate motions.
authors.forename: J A
authors.initials: JA
authors.lastname: Tarduno
authors.forename: M
authors.initials: M
authors.lastname: McWilliams
authors.forename: W V
authors.initials: WV
authors.lastname: Sliter
authors.forename: H E
authors.initials: HE
authors.lastname: Cook
authors.forename: M C
authors.initials: MC
authors.lastname: Blake
authors.forename: I
authors.initials: I
authors.lastname: Premoli-Silva