PLEDGE. 114 PLEISTOCENE PERIOD. sale. An unauthorized sale or misappropriation of the pledge bv the pledjU'ee amounts tu a con- version uf the property lor which the pledj^or may bring his action iu trover or replevin. In many States the hnv of pledge is regulated by statute, and in nearly all the States the power of one in the possession of personal prop- erty to pledge it is much affected by the !• actor Acts (q.v. ). Consult: Colelirook, The Laic of Collateral Securities (2d ed.. Chicago, 1808) ; .Jones, The Law of Pledges (2d ed., Boston, I!)01); Tyler, The Laic of'Cmin/, I'ainis, or Pledges (2d ed., Albany, 1882). Coni])are Hypotiiecatiox. PLEIADE, plA'yAd'. A name assumed by a group of scholarly French poets of the sixteenth century, seven in number, of whom Jean Daurat was master and Konsard the best poet. The others were Belleau. Haif. l)i Hellay, .Jodelle, and I'ontus dc Thiard. Like seven (Jreek poets in the third century B.C. at Alexandria, they took the name I'h'iade, from their number, on nuiking their first declaration of principles, La defense et illustration de la hiiuiue fraiicaise, by Du Bellay (l;')-4!l). This aimed at a revival of classical studies, in the' spirit of I'etrarcli, yet national and patriotic rather than erudite. Of the ethical and philosophic phases of the French Renaissance they were quite .innocent, but its humanism reaches in them Hs fullest expression. (See Bei.i.ay; Bei.leait; Jodelle : RoNSARD. ) Consult Pellissier's chapter on the I'h'iade in Petit de Julleville's Histoire de la langue et de la littfra- iure fran<:nise, which has a good bibliography (Paris. 1806 et seq.) : and essays by Erunctifre in the Revue des Deux Mondes (ib., 1000 et seq.). PLE'IADES (Lat., from Gk.nXetdSej, nXijiiies). In (ireck legend, according to the most general account, the seven daughters of Atlas and I'leionc, the daughter of Oceanus. Of their story there seems to have been no canonical version, but various local legends were adopted by different writers. According to .some they committed sui- cide from grief, either at the death of their sis- ters, the Hyades, or at the fate of their father. Atlas (q.v.) ; according to others, they were companions of Arlemis (Diana), and being pur- sued by Orion (q.v.). were rescued from him by the gods by being translated to the sky. All agree that, after their death or translation, they were transformed into stars. As only six of these stars are easily visible to the naked eye, the story was told that Sterope hid herself from shame that she alone had married a mortal, while her six sisters were' the loves of different gods. Others said that Electra, uKither of Dar- danos b}' Zeus, had withdrawn in grief at the fall of Troy. Their names are Klectra. Maia. Taygete, Alcyone, Ceheno. Sterope (the invisible one), and ilerope. To the (irceks the constellation was important, since with their heliacal rising in Jlay the navigation began, and with their setting in Xovember it was supposed to close. They also served as guides for seedtime and harvest. In astronomy the name designates a group of six stars placed on the shoulder of Taurus, the second sign of the Zodiac, and forming, with the pole- star and the twin. Castor and Pollux, the three angular points of a figure which is nearly an equilateral triangle. Many believe, from the uniform agreement that the Pleiades were seven in number, that the constellation at an early ])eriod contained seven stars, but that one has since disappeared — not a very uncommon occur- rence. PLEIOCENE EPOCH. See I'liocene Epoch. PLEIOSAURTJS, or PLIOSAURTJS. See Plesiusai 1U'.S. PLEISTOCENE PERIOD (from Gk.irXtrcrro!, plcistos, most, superlative of ttoXus, polys, mudi many -|- icaiKSs, kainos, new). The name intro- duced by Sir Charles Lvell to designate that jieriml of geologic time which intervened between the end of the Tertiary and the beginning of the historic period. Within the last few years no other section of the earth's crust perhaps has received so much attention as the strata included under this name, and this is particularly true in America. The term Pleistocene is commonly used as synonymous with Quaternary, although some geologists tend to make two divisions of the tiuaternary, namely. Pleistocene and recent. Other terms which are used are Post-Tertiary, tilacial Period, and Ice Age. One of the most marked features of the Pleistocene was its cold climate and the great development of continental glaciers which formed and spread over a large portion of the glolie as a result of these climatic conditions. The faunal and floral characters of the Pleistocene were not .sullieiently different from those of the Pliocene to have permitted making it a .se])arate division of geologic time on this account, for in those regions which were! not covered by the ice-.sheet we find that plant and animal life apparently continued on uninter- ruptedly from the Pliocene into the Pleistocene. According to Geikie, there were six glacial and five interglacial stages in Europe, while in the United States Chamberlain considers that there ■were five glacial and four interglacial stages. The thickness of the continental ice-sheet nuist no doubt have been enormous, and in some of the mountainous districts in the east we find evi- dence of its presence on the mountains to a height of several thousand feet. The deposits formed by the ice at different localities and under different conditions are very varied, and are kiunvn imder a variety of names, such as oskars. kames. over-wash plains, moraines, etc. The term drift is a general one applied to the deposits laid down either by the ice or by the waters fiowing from it. The classification pro- posed by Chamberlain for the drift deposits is as follows: Wisconsin till sheets (earlier and later). Interglacial deposits (Toronto?). lowan till sheets, Interglacial deposits. Illinois till sheets, Interglacial deposits (Buchanan). Kansan till sheets, Interglacial deposits (Aftonian). Albcrtan drift sheets. In the coastal plain region of the Atlantic States there occurs a great series of Pleistocene gravels and sand, known as the Columbian forma- tion. These are the brick clays still extensively worked around Philadelphia, Baltimore, and Washington. The Pleistocene period was marked by a depres- sion of the land along the Atlantic coast and a temporary drowning of many of the river valleys, such as those of the Hudson River and of the Saint Lawrence. The subsequent elevation gave
