Don't forget to develop the notebook!
d[d0_, a_, x_] := -(d0 + a x ^(1/2))
spreadPlot = Plot[d[2.3, 0.08, x], {x, 0, 1000},
AxesLabel->{"Distance from ridge axis (km)",
"Water depth (km)"}];
spreadingData = {
{0, -2.3},
{300, -3.6},
{600, -4.4},
{900, -4.8}
};
spreadDataPlot = ListPlot[spreadingData, PlotStyle->
{PointSize[0.025], RGBColor[1,0,0]}];
Show[spreadPlot, spreadDataPlot];
explain = Show[Graphics[{PointSize[0.025], RGBColor[1,0,0],
Point[{600, -2.5}]}],
Graphics[
Text[ "Average Water Depth", {880, -2.5}]]];
Show[spreadPlot, spreadDataPlot, explain];