[USMA:14704] Re: Contour lines

[Bruce Raup]

On 2001-07-30 13:18 -0500,  Michael G. Koerner wrote:

> Back in the 1970s and 1980s, the USGS made a BUNCH of 'all SI' 1:25000
> topos covering Massachusetts and parts of other states in the
> northeastern USA, as well as numerous 'all SI' 1:24000 maps from
> elsewhere in the USA.  Their contour intervals were typically 3, 6 and
> 12 meters (depending on the steepness of the terrain that the individual
> maps cover).

Sounds like they chose those to be close to 10, 20, and 40 feet.