The power of ponds

There are moments, rare and sometimes only dawning slowly, when science tears itself away from the trench warfare of lab processing and statistical output, to become an object of compelling fascination. I dare say the slab of drooling clay shown above is not, at first sight, a object of great beauty but the picture speaks of the power of ponds and how the underwater world holds important secrets. The wall of mud and clay is the bed of a little pond that we have cut into from the side, a slice through the sediment. You can see the edge of the original pond at the left and right sides of the image, with a meter rule lying on what was the bottom of the pond before we drained the water. We have stitched together photos from across the width of the cut (hence the floating green box in the sky.... it appears in several of the photos). The slice shows a dark layer, run through with roots and plant debris overlying the paler clay which was the original bed of the pond when it was dug in November 1994 at Hauxley. That black top layer is what we are interested in; the colour suggests a rich seam of orgnaic matter has built up, trapping carbon, a lack of oxygen slowing down decay. We will measure the carbon content precisely, produce tables of data and graphs of trends and gradients, but for now that image has us in its thrall. Pete Gilbert and Scott Taylor thought that slicing through a pond would be a good idea. I thought it would be a muddy mess. Shows how much I know....