Before revision: EBSCOhost, URL Accessed on 20 December 2017 The Scottish map firm John Bartholomew and Son is credited with popularizing the technique, and its color scheme has become conventional: dark greens at low elevations, progressing through yellows and others, to browns and then grays and white at the highest elevations.
After revision: EBSCOhost, URL Accessed on 20 December 2017 The Scottish map firm John Bartholomew and Son is credited with popularizing the technique, and theirthe colored contour line color scheme has become conventional: dark greens at low elevations, progressing through yellows and others, to browns and then grays and white at the highest elevations.