Thalassa; an essay on the depth, temperature, and currents of the ocean . dred miles. No doubt thesea-bottom within a short distance of the shore naturally formsa continuation of the leading features of the adjoining a large plain or a low-lying country will, as a rule,continue its almost level slopes to a considerable distanceout to sea, whilst a range of hills or a chain of mountainsoften extends its steep inclines below the surface of the comparison of the eastern and western coasts of the BritishIslands will afford a ready illustration of the above remarks, andexamples ab
Thalassa; an essay on the depth, temperature, and currents of the ocean . dred miles. No doubt thesea-bottom within a short distance of the shore naturally formsa continuation of the leading features of the adjoining a large plain or a low-lying country will, as a rule,continue its almost level slopes to a considerable distanceout to sea, whilst a range of hills or a chain of mountainsoften extends its steep inclines below the surface of the comparison of the eastern and western coasts of the BritishIslands will afford a ready illustration of the above remarks, andexamples abound in every part of the world. With regard,however, to the more central portions of the bottom of ouroceanic basins, this conception of steep slopes and abruptchanges of level within short distances is not borne out by theform of the numerous oceanic sections which have been sur-veyed. Those who have followed day after day the results ofsounding operations in mid-ocean, along sections measuring CONTOUR-CHART ofthe BOTTOM ofthc ATLANTIC. 100 90 80 70 60 50 40 30 20 10. 60 n iiw F^l Ua Bjvi tid »M HM Ua i-^ taj i-m rm lais [.m k«1 —ctj—jsro- it-M twi is!;i-1!« ;»w KSi ns8ij ^?Ml mw bi BSj KOTfiO100 90 80 70 60 50 40 30 20 10 (J) 10 20 Basin of the Atlantic. 17 several thousand miles, will easily recall the to them familiar factthat, with rare exceptions, and those chiefly occurring in thevicinity of land, the result of one days sounding gave a tolerablyapproximate idea of the depth to be encountered on the followingday. The alteration of level in mid-ocean between two pointsas much as a hundred miles apart is generally so slight that, toan observer standing at the bottom of the sea, the latter wouldappear a perfect plain. Thus the bottom of our larger oceanicbasins is composed of gentle undulations rising and ialling froma few fathoms to two or three miles, in distances extending overmany hundred miles. This view accords with the experienceof the geologist, who finds
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Keywords: ., bookcentury1800, bookdecade1870, bookidthalassa, booksubjectocean
