Archaeologists have speculated that the Dauphin Island shell mounds are "serpentine" in shape, suggesting that the shape might be a religious symbol. Something that may not have been considered in that speculation is the fact that the shape of the mounds could have been determined by the strip mining of the shell mounds for decades during the early 19th century as a source of lime for making mortar during the construction of fortifications on Dauphin Island and Mobile Point. from page LX of House Documents, Otherwise Published as Executive Documents, 13th Congress, 2d Session-49th Congress, 1st Session – 1834-35

"Proposals for supplying bricks and lime were advertised for at Mobile, in 1822, and Captain De Russey, in a letter written to the Engineer Department soon after the proposals were received, stated that 'lime at the kiln will be obtained at fifty cents per barrel;' and in a subsequent letter he represented that an arrangement for 4,000 barrels at that price, received at the kiln, had been entered into. With the accounts of the disbursing officers at Mobile, there are vouchers showing that 2,716 barrels were paid for at that price, and 619 barrels at 62 and one half cents; that the rate paid for the transportation of lime from the shell banks was 18 and three quarter cents per barrel ; and that, thereafter, shell lime was manufactured by the United States, and a compensation at the rate of 12 and one half cents per barrel, amounting to several thousand dollars, paid to L. De Vauberay for superintending the making of it. The contents of a barrel appear to have been about 2 and two third bushels, and at 50 cents per barrel, therefore, without any addition for transportation, the bushel would be 18 and three quarter cents; and Lieutenant Ogden's deposition, it will be seen, declares that it was valued at 20 cents. For the other ingredients, sand and water, the estimate in the proposed award makes no allowance, but, with regard to them, observes, that ' the testimony of Colonel Gadsden, Majors De Russey and Fisher, all state they were under foot, and therefore its cost is nothing.' Colonel Gadsden's answer is as follows : 'Sand and water were both on the spot : the digging of the former, and a well to be sunk (not exceeding 15 feet) for the latter, was the only expense to be incurred.' " https://books.google.com/books?id=_IkFAAAAQAAJ&pg=RA1-PA38&lpg=RA1-PA38&dq=%22de+vauberay%22+%22dauphin+island%22&source=bl&ots=xyveM67UBU&sig=BRl0W9hOnwJosNXuVLXjIzECCdE&hl=en&sa=X&ved=0ahUKEwifp5n5p6bcAhUjSN8KHeNVBi0Q6AEIKTAA#v=onepage&q=%22de%20vauberay%22%20%22dauphin%20island%22&f=false