Measuring Depth

                                               Silas getting a drink from Cottonwood Pond

  Measuring Depth

March 27, 2013

Finally, I was going down to Cottonwood Pond to record its depth.

I wanted to do this before the amount of evaporation would exceed the replenishing of the water, and before very much mud would accumulate on the bottom after falling from the root ball.

The pond is so broad that I cannot reach out far enough to do the simplest method of measurement – sticking a yardstick into the middle.  I had to devise something else.

I found an old broom with a metal handle, some garden twine, and a heavy, flat-bottomed rock from the cairn in my husband's “Mad Monk's Garden” (I know - that's another story...).  I tied the twine firmly around  the rock, then tied the other end of the twine near the end of the broomstick.  Then I rotated the stick to wind the twine around it (raising the rock closer to the stick).

Next, I extended the stick, rock dangling over the spot in the pond that I thought would be the deepest.  I rotated the stick to gradually unwind the twine, lowering the rock into the water.

As soon as I felt the rock touch bottom, I kept the twine taut and held it in place, letting water soak into the twine.

 I carefully raised the rock out of the water, keeping the twine perpendicular to the surface (so that the water mark would not be disturbed) and brought it to where I was standing.  The water line was obvious on the twine, so I tied a red “twistie” to that spot.  After this, I conducted the same procedure in other deep-looking spots.  The red twistie was always well above the water surface, so I knew that I had, indeed, measured the deepest part of the pond on the first attempt.

Next I would take this contraption indoors to “officially” measure.  But, first I did a look-around to see what was going on and what had changed since my last visit:

    Bubbles and a seed cover on the water surface

   A weed dipped in water - roots under the surface?  Or the remains of a seed head?

   Algae covering the fur of the dead Fox Squirrel.  Bubbles form and escape.

  Algae. Bubbles.  Photosynthesis. Oxygen.  

    A new burrow, about two inches in diameter, in the root ball above the pond.

There has been a lack of turbulence lately (no storms or hard rainfall, no in-rushing of extra water, no strong winds), only gentle snow melt.  Fine mud has settled out of the water onto the substrate of dead leaves at the bottom.  This reminded me of the formation of some very detailed, intact fossils.  When ancient oceans were calm, fine sediment settled very slowly on the bottom, gently covering any dead organisms, preserving them in fine detail, leaving even the smallest parts intact.  After millions of years, these leaves could be preserved in the same way.  Every detail I saw that day would be visible in the fossilized leaves.

The water appeared so much clearer this time, and so I wanted to find out how much sediment was still left in it.  I collected a jarful and left it near a log so that the sediment could settle.  I also want to explore that little world in the jar and see what else might be in it.

I went back up to the house and stood a yardstick upright next to a kitchen chair.  I sat the rock on the floor next to the bottom of the yardstick and pulled the twine tautly to see how far the red twistie would reach.

 On March 27, 2013, the deepest part of Cottonwood Pond measured 21½ inches, just 2 ½ inches shy of two feet deep.  

I will measure the depth repeatedly throughout the year and I will, from time to time, record the depth of the pond in this blog. 

I will also be exploring and measuring the width and depth of Life in and around the pond, and the properties of water and mud, from the tiniest organism I am able to see in a basic microscope to the largest visitors, and from the smallest changes that take place to those that have the deepest effect. 

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