The Archipelago series seem to cover a large area of the Andamans, while the Port Blair formation is restricted to the south. The greater part of Rutland Island is formed of serpentine, in which small layers of brown opal have been met with, and which throughout the group seems disseminated with minute crystals of chromium. The Cinques consist of intrusive rocks of serpentine, associated with metamorphosed, indurated, and sedimentary series, mostly calcareous. The rocks of Little Andaman are chiefly lime and sandstone, with a good deal of actual coral rock on the east and south coasts; while occasionally occur outcrops of an igneous nature. At Entry Island and Port Meadows, beds of volcanic origin exist. In view of the connection with them, the apparent barrenness of the Arakan Hills goes to show that little may be expected from the Andamans in the way of mineral products. Amongst others, however, discoveries have been made of lignite, and the ores of chromium, copper, iron, and _sulphur_,[90] although not in quantities that would pay commercial development. It is indubitable, as Kurz has shown,[91] that the Andamans are now undergoing subsidence; but there is ample evidence, in the raised coral beaches that fringe the shores, to show that in the immediate past this has been exceeded by elevation. The islands have been subjected to earthquakes from time to time. The first recorded took place in August 1868, the next in February 1880, and several slight shocks occurred until December 1881, when a severe earthquake visited the group, made itself felt over a large area of the Bengal Sea and surrounding countries, did much damage to masonry at Port Blair, and raised waves 3 feet high, following each other at fifteen-minute intervals for a period of twenty-one hours. Another slight shock was experienced in February 1882. * * * * * The origin of the name Andaman appears to be somewhat doubtful, and it is, of course, a word unknown to the natives. It is, however, very old, and may--as Sir Henry Yule suggests in his Commentary on Marco Polo--perhaps be traced to Ptolemy (who flourished at Alexandria soon after the commencement of the Christian era), and if so, we have by him the first-known reference to the Archipelago, for he mentions a group of islands under the name of Good Fortune, [Greek: Agdaimonos Nêdos], or the like--"The Angdaman Islands"--whence have come the names Agdaman, Angdaman, Andaman. Even at this early date the inhabitants were said to be cannibals. Doubtless the Chinese knew of the group in comparatively early times, for they have records of the neighbouring Nicobar Islands going back for more than a thousand years.