Initial Reports of the Deep Sea Drilling Project - Volume 4

This volume covers Leg 4 of the cruises of the Drilling Vessel Glomar Challenger. Leg 4 of the Glomar Challenger Deep Sea Drilling Project in the Atlantic and Caribbean began in Rio de Janeiro on January 27,1969. During this cruise fifteen holes were drilled at nine sites. The selection of sites and the drilling and coring objectives for each site were based largely upon the recommendations of the JOIDES Atlantic Advisory. Two sites, 25 and 30, were added to the original plan at the discretion of the scientific party while the cruise was in progress. Although the objectives for the individual sites were more or less unrelated to one another, collectively, they were, to enhance knowledge of basins adjacent to continental margins, to investigate sea-floor spreading and the nature of the transverse fractures in the Mid-Atlantic Ridge, to study the geology of island arcs and trenches, and to explore the geologic history of the Caribbean.