All continuously recorded echo-sounding profiles used in preparation of Plates 1 and 20 are shown. Solid lines indicate Lamont Geological Observatory and Woods Hole Oceanographic Institution cruises. Dashed lines indicate soundings supplied by British Admiralty. Lines shown by alternate long dash and two short dashes indicate closely spaced discrete soundings of METEOR.] [Illustration: Heezen _et al._, PL. 22 SIX TRANS-ATLANTIC TOPOGRAPHIC PROFILES Soundings in fathoms continuously recorded by an NMC echo sounder on the R. V. ATLANTIS. The letters a—q indicate where soundings from different cruises were joined.] [Illustration: Heezen _et al._, PL. 23 INDEX CHART SHOWING LOCATIONS OF PROFILES OF PLATES 24, 25, 26 AND FIGURE 45] [Illustration: Heezen _et al._, PL. 24 THIRTY-FOUR PROFILES OF THE CONTINENTAL MARGIN: WESTERN NORTH ATLANTIC Profile locations shown on Plate 23. Note small topographic details. Soundings spaced approximately 1 mile apart.] [Illustration: Heezen _et al._, PL. 25 TWENTY-THREE PROFILES OF THE CONTINENTAL MARGIN OF EUROPE AND AFRICA] [Illustration: Heezen _et al._, PL. 26 CRUSTAL STRUCTURE AND CONTINENTAL-MARGIN PROVINCES FOUR REPRESENTATIVE PROFILES, POSITIONS OF PROFILES SHOWN ON PLATE 23. Data for W-6 from Bentley and Worzel (1956), W-10 and W-11 from Katz and Ewing (1955), and W-33 from Ewing and Worzel (1954) and Officer _et al._ (1957). Seismic data projected to continuously recorded sounding profiles. Vertical exaggeration 40:1.] [Illustration: Heezen _et al._, PL. 27 FIVE TOPOGRAPHIC PROFILES, WESTERN NORTH ATLANTIC Soundings continuously recorded on NMC sounder.] [Illustration: Heezen _et al._, PL. 28 DISTRIBUTION OF DEEP-SEA SANDS IN RELATION TO PHYSIOGRAPHIC PROVINCES Data from Ericson _et al._ (1952; 1955) based on piston cores taken by Lamont Geological Observatory expeditions.] [Illustration: Heezen _et al._, PL. 29 EARTHQUAKE EPICENTERS, NORTH ATLANTIC Date from Gutenberg and Richter (1954) and the epicenter cards of the U.S. Coast and Geodetic Survey through 1956.] [Illustration: Heezen _et al._, PL. 30 LOCATION OF PDR RECORDS AND BOTTOM PHOTOGRAPHS REPRODUCED AS ILLUSTRATIONS.] Transcriber's Notes: The large diagram for plate 1 mentioned in the note on p. v is missing. It was not physically attached to the book per note. Silently corrected simple spelling, grammar, and typographical errors. Retained anachronistic and non-standard spellings as printed. Enclosed italics markup in _underscores_. End of the Project Gutenberg EBook of The Floors of the Ocean: 1. The North Atlantic, by Bruce D. Heezen and Marie Tharp and Maurice Ewing