usgs and mil spec maps use different scales. Usgs is 1:24,000 and I believe the milspec maps are 1:14,000, giving much more detail. Google earth does not provide topographic contour lines, so it is not a decent replacement for a real took map.
Another place to check is local printers who do large format printing, a good number of them are licesnsed to reprint usgs maps. This is how I get mine, though you should reference them for scale as they will sometimes shrink the image to meet margin requirements, nothing that would really mess you up, but it is good to know if trying to make very accurate predictions on trip length.
So, does anybody know where to get military topos? I would love to get detailed maps of our ridge, but I think the maps are considered sensitive documents and not for dissemination.
Google maps has added some contour lines. There is a new button called "terrain" that popped up a couple months ago. It is pretty crappy, though, and not something I would want to trust for any kind of serious hike.
I use topo maps from a commercial supplier in Toowoomba at a good price, use the GPS each year to provide an accurate magnetic variation and mark it on the maps in pencil.
Topo maps only give an estimate of magnetic variation on a yearly basis at the time of printing. Then you have to calculate it at the time of use.
This is very inaccurate and the margin of error increases over distance.
Thanks folks! I am looking for the actual military maps with the contour lines and the grid squares. My boy is in the cub scouts and doing a mini project on map reading. I want to take him a bit further and pass my land nav skills to him and teach him how to find an 8 or 10 digit grid and navigate to it. Could come in usefull for him someday.