Step 3:  Tally's Bluff

Back in your car, continue straight on the road.  At the fork in the road, bear left (you will see a shelter ahead to the right)

After 1.2 miles you will see a high bluff on your left.  Pull your car as far off the road as you can, but be careful.  The drop-off is quite close to the road.
Look at the bottom of the bluff.  The rocks that you see there are called the talus slope.  How do you think they got there?  Estimate the slope of the talus slope.  Compare it with the slope of the bluff.  How do you explain the difference?

Take a look at the rock.  How similar is it to the limestone, chert and shale you saw at earlier stops?

This rock is a puzzle.    It forms thin plates like the Chattanooga Shale (but, of course, not as thin), but unlike shale, it will scratch your knife like chert.  This is the Fort Payne Formation.
The Fort Payne Formation looks like a mixture of shale and chert, because it is a mixture of shale and chert.  Sedimentary rocks can do that.

 

Look at the face of the bluff.  that it has parallel, vertical cracks.  How do you think they formed?

Several forces probably contributed to forming the cracks.  The cracks probably when our continent collided with other plates.  These collissions caused the surface of the earth to form a huge bulge over middle Tennessee called the Nashville Dome.  The cracking has probably increased in recent years, when the erosion of layers above the Fort Payne has caused the area around Nashville to rise like a boat, when its cargo is removed.  This rise is called "isostatic rebound."

 
 
 
 
 
 
 
 
 
 
 
 
 

Now head down the hill.  As you get to the end of the bluff, step down into the gully between the road and the bluff.  Walk slowly down the gully keeping your eyes on the bottom of it.  After a short time, the rock at the bottom of the gully will suddenly change.  What is this new rock?

You should recognize it immediately as the Chattanooga Shale.
Down at Dripping Springs, I argued that finding Chattanooga Shale at the bottom of a bluff didn't necessarily mean that the stratum itself was at the bottom of the bluff.  Look carefully at the shale under your feet.  Does it look like pieces of shale which have fallen from the top of the bluff, or does it look like the stratum itself?
 
 
 
 
 

Now look up on the hill to your right, and look at the trees.  Why do you think that they are bending?  What forces are at work?

Not all mass wasting occurs quickly.  Sometimes rock and soil move down hill at impercievably slow rates.  This is called creep.  Creep can sometimes cause trees to tilt.  The tree's tropisms cause them to grow straight up, and this leads to trees that are bent like these ones.
As you head back to your car look along the top of Tally's Bluff and count your blessings!