These data were obtained from 225 geological survey sites (205 shallow boreholes, and 20 TV grab samples) on slopes of the four guyots in the magellan seamounts. Of these sites, 42 are within Loose deposits on slopes with gradients between 0.4–5.5°, 20 are within Transition deposits(TS) on 3.6–6.0° slopes, 132 are cobalt-rich crust(CS) from slopes at 3.4–37.3°, and 31 are exposed rock(ER) on 15.1–43.7° slopes (Table). Slope gradients and depths of these sample locations were projected onto a scatter diagram. This figure indicates that a gradient of 4.8° maybe the threshold value that controls the distribution of the geologic components on the Magellan seamount slopes, with an error range of ±1.2°, equivalent to a depth error of 4.2m within the 200m horizontal distance. In the error range, twelve unconsolidated samples were misjudged as consolidated ones, i.e., a misjudgement rate of 7.4% (12/163), and six consolidated samples were misjudged as unconsolidated ones, i.e., a misjudgement rate of 14.3% (6/42).

following table is Slope gradient statistical parameters for sampling locations on four Magellan guyots

sediment types Gradients of slope ( o) Sum mean Minimum Maximum ER 31 24.4 15.1 43.7 Sediment1 CS 132 13.9 3.4 37.3 Sediment2 TS 20 4.8 3.6 6.0 Sediment3 LS 42 3.1 0.4 5.5 Total 225 13.3 0.4 43.7

The analysis in Table indicates that CS and ER are preferentially distributed on higher gradient slopes, LS are generally confined to low gradient slopes, and predictably TS are found on slopes with gradients between CS and LS. This implies that there is a range of gradient threshold value (a0) on a seamount slope which influences the type of deposition.
custs01.csv for CS;Rock01.csv for exposed rock; sand01 for loose sediment; TS.csv for tansition zone sediment