The obelisks of St. Peter's at Rome, according to John of Latran, were said to come from the pyramids of Egypt; they are of red granite, which is a kind of rock-stone, and, as we have observed, contains no shells; but the African and Egyptian marble, and the porphyry said to have been cut from the temple of Solomon, and the palaces of the kings of Egypt, and used at Rome in different buildings, are filled with shells. Red porphyry is composed of an infinite number of prickles of the species of echinus, or sea chesnut; they are placed pretty near each other, and form all the small white spots which are in the porphyry. Each of these white spots has a black one in its centre, which is the section of the longitudinal tube of the prickles of the echinus. At Fichen, three leagues from Dijon, in Burgundy, is a red stone perfectly similar in its composition to porphyry, and which differs from it only in hardness, not being more so than marble; it appears almost formed of prickles of the echini, and its beds are of a very great extent. Many beautiful pieces of workmanship have been made of it in this province, and particularly the steps of the pedestal of the equestrian statue of Louis le Grand, at Dijon. This species of stone is also found at Montbard, in Burgundy, where there is an extensive quarry; it is not so hard as marble, contains more of the echini, and less of the red matter. From this it appears that the ancient porphyry of Egypt differs only from that of Burgundy in the degree of hardness, and the number of the points of the echini. With respect to what the curious call green porphyry, I rather suppose it to be a granite than a porphyry; it is not composed of spots like the red porphyry, and its substance appears to be similar to that of a common granite. In Tuscany, in the stone with which the ancient walls of Volatera were built, there are a great quantity of shells, and this wall was built 2500 years ago. Most marbles, porphyries, and other stones of the most ancient buildings, contain shells and other wrecks of marine productions, as well as the marble we at present take from the quarry; therefore it cannot be doubted, independent even of the sacred testimony of holy writ, that before the deluge the earth was composed of the same materials at it is at present.