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
The QGIS package
The "GeoTIFF" option in the above list of options for map formats sends
me into a big long rabbit hole.
I have dabbled with GIS software in the past, and backed off once
I began to learn that GIS is a universe unto itself.
Now I am in a mood to persevere.
It looks like QGIS is the best open source option without fees.
Using arcGIS is out of the question for an individual,
unless they are wealthy.
To get started, I just want to view the GeoTIFF and see what layers might
be offered. But learning how to use QGIS promises to open the door to many
things I might find useful and worthwhile.
See the link above.
Feedback? Questions?
Drop me a line!
Tom's Geology Info / tom@mmto.org