These sediments were formed in an arid, enclosed shallow seaway or saline lake between 230 and 215 million years ago.
The continental arrangement, with its equatorial seaway, was partially responsible, in that it limited the oceanic circulation.
Water from the Great Lakes will empty into the Gulf of Mexico, as opposed to the St. Lawrence Seaway.
All compasses are fitted with a gimbal ring to keep the bowl and card level under every circumstance of a ship's motion in a seaway, the ring being connected with the binnacle or pedestal by means of journals or knife edges.