In other parts of America prehistoric races have left behind them huge earthworks, lofty masses which were probably fortifications (Fig. 5), temples, and sepulchral monuments (Fig. 6). These earthworks extend throughout North America from the Alleghany Mountains to the Atlantic, from the great lakes of Canada to the Gulf of Mexico. The name of the people who erected them is lost, and we must be content with that of Mound Builders, which commemorate their vast undertakings. [Illustration: 7.] Ground plan of a pueblo of the Mac-Elmo Valley. At a period probably nearer our own, Arizona and New Mexico were occupied by other maces, who built the so-called _pueblos_, which were regular phalansteries, or communal dwellings, each member of the tribe having to be content with one wretched little cell (Fig. 7). At some distance from the men of the _pueblos_ lived the Cliff Dwellers, about whom we know next to nothing; a few stone weapons and countless fragments of pottery being all they have left behind them. These men established themselves in situations which are now inaccessible, hewing out a dwelling in the rocks on the mountains (Figs. 8 and 9) with wonderful perseverance, and closing up the approaches with adobes or sun-dried bricks, making incredible efforts to obtain for their families what must have been at the best but a precarious shelter.46 These prehistoric races were succeeded in America by the Toltecs, Aztecs, Chibcas, and Peruvians, all known in history, though their origin is as much involved in obscurity as that of their predecessors. Temples, palaces, and magnificent monuments tell of the wealth which gold gives, a wealth, alas, which also enervated the vital forces, so that the Spanish and Portuguese met with but little serious resistance in their rapid conquests. [Illustration: 8.] Cliff-house on the Rio Mancos. [Illustration: 9.] House in a rock of the Montezuma Cañon. Such are the facts with which we have to deal. In the following chapters we shall consider more at length the problems they present, but already we are led to one important conclusion: in every part of the globe, in every latitude, in every climate, worked flints, whether but roughly chipped or elaborately polished, present analogies which must strike the most superficial observer. “We find them,” remarks an American author, “in the tumuli of Siberia, in the tombs of Egypt, in the soil of Greece, beneath the rude monuments of Scandinavia; but whether they come front Europe or Asia, from Africa or America, they are so much alike in form, in material, and in workmanship, that they might easily be taken for the work of the same men.”