The posted coordinates are actually on the sidewalk of
the street that parallels the freeway. Do not attempt to stop
on the freeway or the road. Find a parking spot before or
after and walk back to the coordinates along the sidewalk.
Inverted topography is a geomorphologic feature that describes
topographic high points that were once ancient valleys. To form
this example of inverted topography, lava initially filled an
ancient canyon where it cooled and formed a hard weather resistant
basalt. The surrounding sandstone eroded away more quickly leaving
the basalt higher than the surrounding area. Thus the former canyon
turned into the ridge, inverting the topography.
Figure Source Utah Geological Survey
(http://geology.utah.gov/surveynotes/geosights/invertedtopo.htm)
The freeway cuts perpendicular to the ancient valley, so the
road cut provides an excellent cross section of the feature. The
flat top of the hill is the basalt and the bottom of the ancient
valley.
Logging requirements:
Send me a note with :
- The text "GC15FGQ St. George Inverted Topography" on the first
line
- The number of people in your group.
- Which side of ridge is the current stream channel
- Estimated thickness of sandstone has been eroded from the
ancient stream channel.
The above information was compiled from the
following sources:
- Utah Geological Survey, Inverted Topography in
the St. George Area of Washington County,
http://geology.utah.gov/surveynotes/geosights/invertedtopo.htm