a . Alan Cutler, The Seashell on the Mountaintop (New York: Dutton, 2003).
u “Nothing is so high, nothing is so far from the sea that we cannot find [shells] of those creatures that only live in sea water.” Jan Van Gorp (1569), as quoted by Cutler, p. 59.
u John Woodward, An Essay Towards a Natural History of the Earth (London: 1695; reprint, New York: Arno Press, 1978), pp. 3–74.
b . During the period 1508 to 1515, Leonardo da Vinci carefully studied the shells he found high in Italy’s Appennines Mountains. He raised valid arguments against all the hypotheses that others were proposing to explain seashells on mountaintops, but he offered no explanation of his own. [See Leonardo da Vinci, The Notebooks of Leonardo Da Vinci, Vol. 2, editor Jean Paul Richter (New York: Dover Publications, 1970), pp. 208–218.]
c . For example, Voltaire wrote, “It always astonishes me that some refuse to allow that the earth produces these stones.” Cutler, p. 195.
d . Twelve years before Thomas Jefferson became President of the United States, he was the U.S. Ambassador to France. In June of 1787, he traveled to the mountains near Tours, France to see dense deposits of clam shells 15,000 feet above sea level. Some, including Voltaire, had claimed that those shells were actually growing as “fruit of the earth.” After examining the deposit, Jefferson disagreed and wrote, The “origin of shells in high places [might be one of those questions] beyond the investigation of human sagacity.” [See H. A. Washington, The Writings of Thomas Jefferson, Vol. 9, (New York: Riker, Thorne & Co., 1854), p. 366.]