GEOL 103 Lecture 4: Developing the Plate Tectonics Theory
3 Sep 2019
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Document Summary
"modern" measurements of ocean depths greatly increased in the 19th century, when deep-sea line soundings (bathymetric surveys) were routinely made in the atlantic and caribbean. In 1855, a bathymetric chart published by u. s. navy lieutenant matthew maury revealed the first evidence of underwater mountains in the central atlantic (which he called "middle ground"). This was later confirmed by survey ships laying the trans-atlantic telegraph cable. Time graphs of the returned signals revealed that the ocean floor was much more rugged than previously thought. Such echo-sounding measurements clearly demonstrated the continuity and roughness of the submarine mountain chain in the central atlantic (later called the mid-atlantic. In 1947, seismologists on the u. s. research ship atlantis found that the sediment layer on the floor of the atlantic was much thinner than originally thought. Scientists had previously believed that the oceans have existed for at least 4 billion years, so therefore the sediment layer should have been very thick.
