Old Geology Mapping Method

I am in the process of moving which means going through stuff in the closet. In the back corner was a long cardboard tube. Inside were two large mylar sheets. One sheet was a mylar of all or parts of 12 7.5-minute topographic quadrangles. I had cut the original paper maps and spliced them together and then had copy business produce several large mylars from the original. Another mylar sheet was then overlaid on the base mylar map and was notated with geology contacts and measurements. Large paper maps at 1:24,000 scale could then be produced from the original mylars.    

Portion of the mylar overlays (Cascade Pass area) 

My biggest challenge was the size of the map area covered much more than the light table used to mark it up. I recall thinking afterwards it would have been better to have had multiple quad maps that would have been easier to manage.

Obviously a lot has changed in geology map production since the map tube got propped in the back of the closet - mostly for far better products that are much easier to access and read.