Marathon Expedition Leg 4


KGWU Thomas Washington 171630 July ‘84 Weekly Science Report Began surveying
yesterday.  Early results inconclusive. W. Menard/R. Hey


Thomas Washington 241800Z July ’84.  Finding many abrupt changes in trend of
abyssal hills and no gradual changes.  This suggests that changes in the
direction of seafloor spreading are accommodated by propagating rifts.  Now
surveying change in trend of surveyor fracture zone.  Menard/Hey


KGWU Thomas Washington 011745Z July ’84.  Continuing Seabeam survey.  Surveyor
fracture zone traced as an uninterrupted curving trough while direction of sea
floor spreading changed.  Also traced mighty Mendocino Escarpment to its origin
as a little cliff.  Menard/Hey


KGWU T. Washington 071745z August 84 Weekly Report. Used SeaBeam to map abyssal
hills and major structures where Mendocino Fracture Zone changes trend. When
fracture zone had old trend there were several parallel troughs and scarps,
presumably with ridge offsets between them. There were altered to one great
escarpment with one offset when the trend changed. On way to Oahu have surveyed
short lenths of the Murray Fracture Zone and Bach and Beethoven Ridges.
(Menard/Hev)