Several years ago, ground fissures were opening up and
the Arizona Geological Survey started to
investigate the causes of these fissures. Several previous unknown
fissures were reported in an area
East of Flagstaff, Arizona near the Arizona Meteor Crater. I decided to
map the area, using Google Earth images
The bright dot near the center of this photo is the
4000 foot-wide Arizona Meteor Crater.
Using the measuring tool that comes with Google Earth,
I zoomed in and marked all of the visible
drainage channels with white lines. Fissures were mapped with green lines.
The photo was also cropped,
sharpened and the contrast was increased.
While I was still on Google Earth, I used another
tool that showed what the map are would look like at
midnight. Obviously, the scenery all turned black and disappeared.
Only the white and green lines that
I had drawn were still there. Again the photo was cropped showing the same
area as the previous photo.
The drainage pattern and the location of fissures strongly stands out.
However, it doesn't look like a
order to change the previous view to something tht looks like a line drawing, I
used a tool on my
graphics program to reverse colors. The black background turned white and
the white lines representing
the drainage patter turned black. The green lines indicating fissures
Carefully studying the drainage pattern from the
previous view, I detected a double-ring structure that
affected the drainage pattern. I have no theory as to its cause.
Something to work on. Somewhat
surprising is that the meteor crater impact did not create any fractures or
joints in the surrounding area
that show up in the drainage pattern.
is a view of the same area with just the fissures outlined. The position
of the fissures are
controlled by a pervasive joint pattern.
Using Google Earth, I rotated the photo so that North
is to the right. This gives a better view of the
Again, I used the daylight function to see what the
area looks like at night. This action replaces the
scenery with black.
Next, I used my graphics program to reverse colors,
creating a line map of the drainage pattern.
This view shows the scenery, drainage pattern and links
Removing the drainage pattern, the linear
nature of the the fissure outcrops can be highlighted.
Just credit photos to Google Earth/R.Weller/Cochise College.