over at a canoeing site we were posting our various ways of dealing with maps..some just used the sheets as they came and switched from one to another. others cut the maps into 8x10 sheets and put them into a plastic folder.
i posted this---

my entire trip on one huge sheet taped together from trimmed maps to fit my traveling area..thats a 48 inch stick at the bottom..the map paper is waterproof and very tough..you can't really rip it by hand..so it was suggested by someone who thought it might be too big that i could always use it as a tarp to save weight...sooooo--
what do you think..ties a the corners or put a slit in it and use it for a poncho???

Under normal circumstances I wouldn't want to use my map as a tarp. It just increases the chances of a piece of critical gear being lost or destroyed. However, the army does make survival maps that are printed with local edible plants and a few other pieces of information. They're printed on tyvek and are meant to be used as a tarp in a pinch. I don't know of any source for them, since I've only seen one as a wall decoration.

Tarp it! But I'd suggest buying some tarp clips, adn avoid interrupting the integrity of the map/tarp with holes.

Where do you get your waterproof maps? Do you know if they make them for other countries?

For years I've been packing in materials to erect signs in remote places, like the directional cairns built by inuit and desert areas in Eurasia.
Mine are a takeoff on Shopping Mall 'YOU ARE HERE' signs. No other superfluous information, but surely a comfort to lost souls.

I've got it! Put grommets at each corner, two poles, and you have an alpha tent . Put the map side down, you could lay in the sack and plan tomorrow's route!!!

I agree with Mdinana- use tarp clips, I use them even with grommeted tarps.

AROTC--the maps are made by McKenzie and as far as i know only cover the canoe counrty in Northern Minnesota--the BWCA and Quetico Park in Canada which is just across the border from the BWCA..