stone age is shown by the fact that some of the skulls found in them, notably two from a mound near Kiahkta, south of Lake Baikal, are of the prehistoric rather than of the Mongolian type. Mongolian skulls belong to the brachycephalic type, in which the breadth is more than 80 per cent of the length, but the two mentioned were distinctly dolicho-cephalic type, the breadth being a trifle over 73 per cent only of the length. In the Irkutsk museum may be seen many implements of stone, bone, and of hand-beaten copper ornaments which have been found in the burial mounds of Siberia. Implements of stone, bone, and rude hand-wrought native copper are precisely what was found in the burial mounds of the Calipooia, as will be later shown.
A mound having no bronze or iron implements or coins, and no manufactured article of modern times, having only the products of the stone age, and its builders of an unknown and vanished race, is termed a prehistoric mound, and that is the term to apply to the mounds of Linn county and of the Willamette valley. The museums of Siberia, and particularly that at Vladivostok, are rich in materials taken from the prehistoric burial mounds of that section. All things point to a line of migration open in prehistoric times through Siberia across Bering strait into North America, over which there was free movement both for man and for the unwieldy mammoth, whose remains are found with man's al around the northern hemisphere, from Alaska eastward to Great Britain, and on through northern Europe and Asia back to Alaska. Mounds along the Willamette river and its tributaries, including the Calipooia river, have been known as Indian mounds since the first arrival of white settlers in Oregon, but the Indians here, as well as those in other places, disclaim any knowledge of the origin of the mounds.
