Two years later, in 1884, I was employed by the late Professor Marsh to explore this same fossil bed. The bones which I was after now were covered by fourteen feet of moulding sand and a four-foot ledge of hard rock, the heavier bones lying on the sandstone, the lighter ones mingled with the sand above. This sand and rock had to be removed by pick and scraper, which meant that there was a large amount of heavy labor before us. Therefore, having more means at my command than I had had before, I drove up to Mr. Overton’s door and offered him forty dollars a month to work for us with his team during the whole summer, with the understanding that I was to have all the fossils found. This offer he gladly accepted, and I found him a very careful worker. Not only did he do the rough work well, but when we got a floor laid bare above the bones, he proved to be a most careful collector. My other assistant on this expedition was a Mr. Will Russ, who afterwards became a skilful dentist.
Our method of work was first to cut down and remove the sand and rock for a space twenty feet wide and perhaps a hundred long, using a plow and scraper. Then we cleaned up our floor and uncovered the bones with oyster knives and other tools which we had made to suit our purpose. One, I remember, was a hoe straightened out at the shank and cut off at the corners to make a diamond-shaped tool. With this we could work under the high bank, and take out specimens which we could not reach otherwise. Trowels and diggers of various patterns were used also.
The bones which we were collecting lay scattered along both sides of the ravine for a quarter of a mile, often in pockets or pot-holes in the gray sandstone. Of this there are two layers, about fourteen feet apart, the interspace being filled with beds of fine moulding sand, with some whiting from the underlying chalk, which constituted the land surface when these fresh-water beds were deposited. There are also beds of sand that have been washed clean by the currents of the flood-plain of some ancient river, for the exposed section shows all the different deposits of an overflowed valley. Above the washed sand is a stratum of sand and clay, indicating that here was a quiet place where the muddy backwater deposited its load. This layer, upon exposure, cracks in all directions, like the mud at the bottom of a puddle after the water has evaporated.