I wonder if that's not a typo for "40 feet" contours...
https://pubs.usgs.gov/of/2001/0311/pdf/cuc_map.pdf

--Robert


Angela R Cope wrote:
>
>
>
>
> ------------------------------------------------------------------------
> *From:* Diaz, Tony A. <[log in to unmask]>
> *Sent:* Wednesday, October 19, 2016 11:21 AM
> *To:* 'Maps-L: Map Librarians, etc.'
> *Subject:* 4 ft contour maps?
>
> Does anyone know of local topo maps with 4 ft contour intervals? 
> Specifically, I'm looking for info on the area within the Cucamonga 
> Peak (CA) 7.5' Quad. I came across an uncited reference to such a map, 
> but I can't find anything.
>
>
> Tony Diaz
>
> caltech
>