When using the Profile Tool plugin I get a graph that looks like the 2nd derivative of what I want. That is, it looks like the rate of change of the slope of the elevation profile. I just want the elevation profile! The data is present for good 1' contour lines. Why is the Profile Tool interpreting the data in such a bizarre way? What am I missing? And what are the Min and Max units?
Looks like you are getting a profile of your raster image (aerial photo?).
The profile tool works on raster data not on vector data (i.e contours):
"This tool plots profile lines from raster layers"
To get a profile, you need to use a raster DEM as input.