collection of small stones, a part of which were then embedded in the bank.”[135] Near these fire-places the writer of the above found the membranous covering of common river shells (the Unios). We think that no geologist familiar with the constant changes of the Ohio River bed, will consider that the conditions surrounding these ancient fire-places warrant us in assigning them a much greater antiquity than we attach to the Mound-builders’ works in the neighborhood. In 1846, Sir Charles Lyell, when at New Orleans, made an estimate of the time required to account for the immense annual deposit of the Mississippi River in the neighborhood of its delta. From a computation based on certain data, which assumed the area of the alluvial plain which is the result of those deposits, to equal 30,000 square miles, several hundred feet thick in some places, he estimated that probably 100,000 years would be requisite.[136] Subsequently, during the process of excavating for the New Orleans Gas Works, it was found necessary to cut through four buried cypress forests. At the depth of sixteen feet and on the fourth forest level, a human skeleton distinctly of the Indian type,[137] was found under the roots of a cypress tree, together with burnt wood. Dr. Dowler, dividing the history of the delta into, 1. The epoch of grasses or aquatic plants; 2. That of the cypress (_Taxodium distichum_) basins, and 3. That of the live-oak platform, tabulates the age of the strata overlying the skeleton as follows: Epoch of aquatic plants 1,500 years Epoch of the cypress basin, in which he assumes only two successive growths 11,400 „ Epoch of live-oak platform 1,500 „ —————— Total 14,400 years