Using the code below (based on 'Modern Applied Statistics with S (4th Edition)from Venables,Ripley) for a 2*2 contour (plus color) plot, the top left contour plot is distorted in the sense that the contour plot is compressed in x-direction, while the axis and the contour plot in y-direction display correctly. Any idea how to fix this anomaly ? Best wishes, Berthold ... par(mfrow = c(2,2), pty ="s") topo.ls <- surf.ls(3,RALV,RARV,PP) trsurf <- trmat(topo.ls,80,160,80,160,100) eqscplot(trsurf,xlab="RALV",ylab="RARV",type="n") image(trsurf,col=terrain.colors(100),add=T) contour(trsurf, lty="solid", add=TRUE) points(RALV,RARV) title("PP") topo.ls <- (replication of the same block as above 3 times with different variables) ...