The Ocean 13 



usually allow considerable elbow-room for the use of ideas and speculations on the 

 bottom topography afforded by other knowledge (for example, geological). In par- 

 ticular, the construction of the isobaths requires good use of oceanographic view- 

 points. The distribution of temperature and salinity at the sea bottom and in the 

 water immediately above it are dependent on the bottom topography and often 

 allow greater accuracy than is possible from the records of depths alone, for example 

 in the determination of depths on saddle points or the position of cross-ridges and 

 others. Indicators such as these of the course of the isobaths are always valuable and 

 deserve full attention. In this connection, see especially Stocks and Wust (1935) in 

 the addenda to the chart of the Atlantic Ocean in the "Meteor" volumes. 



Good charts are not available at the present time for all the oceans and adjacent 

 seas; it is to be expected that there will be considerable improvement here in the future. 

 Apart from the older depth charts in the Sailing Directions for single oceans and 

 charts produced by single expeditions the following may be noted : 



(1) The Carte Generale Bathymetriqiie des Oceans, scale 1 : 10 million, produced 

 by the Hydrographic Bureau in Monaco; 16 sheets on Mercator projection: 

 second edition, 1911-30, third edition from 1935. 



(2) The ocean chart published by Groll (1912) in which all depths available up 

 to that time were interpreted in a uniform way and used for careful construction 

 of the isobaths; equal-area projection on a scale of 1 : 40 million, 



(3) The chart of the total Atlantic Ocean on the records of the "Meteor"; a general 

 chart, 1 : 20 milHon on the Lambert equal-area azimuthal projection with iso- 

 baths at 500 m intervals (Stocks and Wust, 1935). In addition to this there is a 

 basic chart of oceanic soundings on a scale of 1 : 5 million in 1 3 sheets (4 sheets 

 published, Stocks, 1937) showing all the critically checked soundings in this 

 ocean. 



(4) A more recent chart of the Indian and Pacific Oceans has been given by Schott 

 (1935) on an equal-area projection, on a scale of 1 : 60 million, with the nature 

 of the bottom topography of these oceans indicated with sufficient accuracy. 



(5) An excellent chart of the sea bottom topography of East-Indian Seas was con- 

 structed by VAN RiEL (1934) and was published in the scientific results of the 

 "W. Snellius" Expedition. 



For more recent charts of parts of the oceans and adjacent seas, see the sections on 

 the special morphology of these areas. The charts accompanying this book(Plate 1) give 

 a summary of what is known of the main features of bottom topography of the oceans. 

 Much of the knowledge obtained by more recent expeditions by echo sounding has 

 been taken into consideration here, in so far as the small scale will allow. In these 

 charts the isobaths are drawn for every 1000 m and the 200 m isobath has been shown 

 where the scale permits to show the limits of the continental shelf. The coloration 

 of the depth-intervals gives a clear picture of the general bottom topography in spite 

 of the confusion of fines at some points. In order to make the characteristic bottom 

 configurations such as deep-sea basins, troughs and ridges and of the cross-ridges, 

 deep-sea canyons and other forms which may occur, more visible, a somewhat 

 schematic chart has been prepared and is reproduced in Plate 2 (Defant, 1947). All 

 the important peculiarities of bottom topography of the ocean have been indicated by 

 letters and numbers. 



