July 23, 2026
Software for Geologic Maps
The Santa Rita maps (Mt. Wrightson and Sahuarita quads) were mapped in 1971
by Harold Drewes from the USGS.
Given that this was 50 years ago, the maps were published as paper sheets
which were then scanned.
The USGS now offers these scans in 4 forms.
JPG (1M)
KMZ (2M) for Google Earth
PDF (14M) they say "print optimized"
TIFF (27M) they call this GeoTiff
GeoTiff viewing software
The QGIS package
For my linux system a recommended package is qgis and I find it available in the
standard Fedora package set. Installing it pulls in 32 packages, mostly python3
and qt5 libraries of one sort or the other.
I launch it and get a few Gtk warnings. This will be a signficant learning curve.
There are plenty of tutorials.
Some videos are made by people in India, and while they may have good content,
I find them a struggle to listen to.
A brief summary is:
Launch a new project.
Use the Browser Panel to locate your spatial datasets, and drag them onto the map canvas.
Double-click any layer in the Layers Panel to adjust colors, symbols, or labels.
Use the Print Layout tool to create a finished map.
Geotiff.io
This is online and browser based, so let's give it a try.
I tell it to upload my file and there is a long wait while it says "Loading Raster".
The TIF is a 29M file, so this is not entirely surprising.
Feedback? Questions?
Drop me a line!
Tom's Geology Info / tom@mmto.org