Cradle knolls

[Jeff]

Here is something I have always wondered. What creates "cradle knolls". I have always thought that it was caused by trees tipping over in poor soil and then rotting away leaving the depressions. One of the guys at work today said he thought they were remnants of prehistoric wave action from a long gone ocean. Any facts out there??

[Forester Frank]

Jeff:
What you describe, I know as "pit and mound" topography. This occurs when a tree bows over, roots and all, then deteriorates into the soil. The deteriorated rootball is the "mound", the depression left is the "pit".

You will see this in an area that suffered severe wind throw in past years.

I have not heard of cradle knolls, but the ripple effect of the topography along coastal areas sounds like what you describe. A good place to see this is where the Ocqueoc River flows into Lake Huron (between Roger City and Cheboygan, MI).

This area has rises and falls of what I call sand dunes. On the rise grows jack pine and red pine, and in the dip grows balsam fir, black spruce,  and cedar.

The topography is very evident when viewing an air photo of the area. Check it out!

Good question.

[Jeff]

I spent one summer working in the woods in the early 80's because our mill had no work. I ran a small bobcat with a feller buncher on the front. We were in 70 and 80 foot aspen, probably 15 to 20 dbh. This area was ALL Cradle Knolls. In order to lay those big aspen down you had to be able to spin the bobcat with the weight. In those knolls you could not. I got flopped on my side more then I can remember because I could not turn and let go of the tree. It seemed like fun then as a young buck, but boy, it seems like suicide now.

  The other thought about those knolls from when I was a kid. Was hiding a deer in one just long enough to find my dad. Came back and searched for an hour to find the hole with my deer...

[Forester Frank]

Don't see too many Bobcat shears anymore. I think they could still be used effectively in young pine stands (thinning).

It's funny how the things we used to do for fun when we were younger seem dangerous to us today.

Still a little unsure about cradle knolls.

Frank

[Ron Scott]

Frank is correct. A cradle knoll is the pit and mound microtopography formed as a result of a tree uprooting and its holding soil displaced, thus the resulting microreleaf. Cradle knolls usually occur in forest areas subject to windthrow and result in the landscape characteristics created from the tree's shape, size etc. They usually provide evidence of natural disturbance.

[Theguide]

Jeff,

Frank is right on top of this.  In the South, Hurricane Andrew created a major collection of "cradle knolls".  In Alabama, it is a major result of wind throw.....

Read about it here:
http://www.fiu.edu/~serp1/projects/windthrow/windthrow.html

Steve Nix
About Forestry Guide
forestry.about.com

[Texas Ranger]

Steve Nix is a Newbee?

Any way, down south the cradle mounds are caused by wind throw, which exposes a "clay root" for a period of years until it washes down.  Big old hard wood goes over, roots and clay pull up and mound up well over 6 feet.  Over the years it melts back down.  Pine is differenct, tap root.  So after the tree is dead, a fire goes through, and you have a perfect round hole where the root burns out.  I went into one with one leg and spent a week in the hospital getting fixed.

I love my job in the woods.

[SwampDonkey]

I agree with you guys on this cradle - knoll thing. But it brings to mind of an area of our province that looks like the sahara desert, only it's covered with spruce and jack pine trees. You can see the wave effect real good with a stereo pair of aerial photos. I tried to retrieve some aerial views off the government website, but the photos aren't yet digitized for that area. I know on the ground there are these sharp knolls all through the woods where people take sand from. Not a stone in it, just fine sand like being on the beech. ;D

[Deadwood]

Hey Jeff, I was surprised you used the term Cradle-Knolls, that is a term we used here in Maine, but I thought it was indicative of this area. In any case, I knew exactly what you were talking about.

We to a have location on our property filled with cradle-knolls. Real hard to log with anything but a skidder. I did use a bulldozer though and made a few smooth logging roads so my Kubota could navagate it. In using the bulldozer I found that despite being very large Eastern Hemlock stumps, they popped right out of the ground. Ledge is only a few feet down and I surmise being on a hill, the long branches of the hemlocks act as sails and easily tip over.

Here is a picture, though it's kind of hard to see the cradle knolls in all the vegatation.


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