Trail Trivia

A bit of trail trivia for you. First I’ll post some pictures to see if anyone volunteers an answer as to what’s going on in them. I’ll put the answers at the end of this post. Click on the pics to enlarge.

(1)

Here is another version:

(2)

And another:

(3)

Something different. What caused all these cracks?

(4)

Seen on the side of the slope.

(5)

Another:

(6)

Why did this tree fall?

(7) IMG_20150412_101512439

What is this?

(8)

You can probably guess this one.

(9)

Why are these embedded rocks smooth and round?

(10)

What the hey?

(11)

Answers:

1, 2 and 3: When I first noticed this phenomenon some years ago I was momentarily stumped. What is happening is that on windy days the branches and stems touching the ground are being swept back and forth creating this half-circle pattern in the dirt. In the first one, it actually dug grooves in the ground. This was after that very windy day that I mentioned in a previous post. 4. This is sandstone, a relatively soft rock. When it rains and is simultaneously freezing weather, water gets into the cracks and then expands. This is called Frost Wedging. 5. and 6. Rain falling steadily from the leaves of trees above create this little pitting pattern on the sides of slopes below. You can see where small rocks and a long stem shielded the ground under them. 7. The precipitator was a long soaking rain that softened the ground enough. Strong wind can do it too. 8. Strata, layers of sand laid down horizontally, then subsequently thrust up by geologic action. These layers are like pages in the book of time. 9. Beaver :-B 10. These common rocks, like many people find on trails well inland, have been eroded by the action of water and time. It is constant rolling in ocean waves over the sea bed and on beaches, and inland in rivers and streams, helped by the abrasive action of flowing sand and rubbing against each other that rounds off the edges of once hard edged rocks. Of course over time the shoreline can advance or recede, sometimes hundreds of miles and rocks may be buried. Later the land may be thrust up at odd angles by earth movement, and those rocks, once buried, re-exposed.

11. When I first saw these mysterious holes regularly spaced high up the side of a sea cliff I had to scratch my head. This formation is vertical and, now, far from the tide, having been pushed up sideways by past geologic action. What could have precipitated these regularly shaped carvings? Turns out they were made by sea urchins. These small, spiny animals have five, ever sharpening teeth on their bottoms that they use to dig into limestone rock at the tideline. These holes are great for, one, protection from their fish and otter predators. Only their hard, sharp spines protruding, and two, stability from the ever moving waves. The above picture is of long abandoned, likely prehistoric urchin homes. Today they still live in these carvings. A picture I took not long ago:

And closer:

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