<HTML>Keith,
I'd like Graham to spend some time in the field looking at something BESIDES sites that someone has told him are artifacts. If he could give examples of what kinds of "odd" geology he doesn't think were made by humans, I'd be more comfortable with those he claims were.
I can think of dozens of instances where geological processes have created exposures and formations that express remarkable symmetry and uniformity. There are amazing limestones in Glacier National Park (Apekunny Formation, IIRC), that are jointed at 90 degrees in all three planes of intersection - perfect building blocks. However, unless the LC was around 1.3 BILLION years ago, they're NOT an artifact. Columnar jointed basalts are another example. Aren't there some exposures of these along the coast of Scotland which the locals concluded were erected by giants? I don't remember how old these are, but I'm pretty sure they are not from the Quaternary.
But my favorite example is the "rock art" I found as an enthusiastic field school student. I was surveying a talus slope below an exposure of Columbia River Basalt and spotted a boulder with three nearly perfect concentric circles on it. Boy was I excited! Called the prof over to see . . . he hummed and hawed a bit, being kind, I suspect, and then explained spherical weathering. This process can, under certain conditions, create layers of weakness in otherwise solid rock. What he concluded was that this boulder had spherically weathered and a second, smaller rock had fallen off the cliff and hit it, blasting out a crater which exposed the three weakened layers in the walls of the crater. Subsequent weathering had partially smoothed out the crater and accentuating the concentric rings. Of course, it could still have been rock art, concentric circles are a common motif, but we didn't find any other art in the area (as Garrett says - context is everything). And we did find many other examples of spherical weathering, just nothing as symmetrical as the three ring rock.</HTML>
