Friday, April 1, 2011

Cutoff Pool

I’m still enjoying the abundance of water that is found at Blue Jay Barrens during this time of year. It would really be nice to have more temporary pools suitable for amphibian breeding. Here’s a pool that looks like it’s ideally suited for that purpose.
This pool is a fairly recent creation. Until a few years ago, it was part of the main creek channel and did not have any quiet water in the pool. It is slowly undergoing a change from a stream ecosystem to a temporary pool ecosystem.

The water used to come from the upper left and drop as a waterfall into the pool. The action of the falling water is what originally created to pool. The collection of undisturbed leaves shows that even with the excessive rains we’ve had during the past two months, no water has crossed over into the old creek channel.

That collection of tree trunks is what caused the creek to change direction and take a sharp turn to the left. The new route took the stream over a layer of sand and fine gravel that quickly eroded until the creek was flowing across a stable bedrock layer.

The new channel to the left has enlarged to the point where it takes a major flood event to cause water to flow through the old channel toward the isolated pool.

Downstream, you can still see the shape of the old channel. The elevation of the pool is high enough that flood water cannot rise to the point that it enters from this end. The pool can now be considered isolated from the creek’s influence. Whether or not it will meet the requirements for breeding amphibians is yet to be seen. I certainly hope it does.


  1. Your images bring back such great images of fun in the woods as a kid. We would spend hours turning over rocks in the creek to see what little critters we could find there. Ah, childhood.

  2. I have similar memories, Lois. However, I think the same activities are more fun as an adult. I don't have to ask permission to go to the creek, I don't get into trouble for getting wet and muddy and I don't have to stop what I'm doing because someone set a time that I had to be home. As a kid, I always thought it would be so much more fun if I just had more control over my life. I was right.

  3. Your blog entry reminded me of something I've studied about Ice Age river systems in what's now Georgia. During the last glacial maximum the climate became more arid because much of the planet's water was locked in ice. Today, Georgia's rivers meander all over the place, but during the LGM, as the water table dropped, the rivers became braided with many cut-off channels and sandbars. Their were probably a lot of isolated pools for amphibians to breed in then.

  4. You're probably right, Mark. I'm in an area where thin sheets of ice advanced from the leading edge of the last glaciation. The ice sheered off the hilltops and left level areas that developed vernal pools that are now used by breeding amphibians.