WAVE EROSION OF GEOMORPHIC SURFACES, DEPOSITION OF ERRATICS, MASTODON AND WOOLY MAMMOTH OCCURRENCE, AND DEPOSITION OF MALPASS STRATIGRAPHIC UNIT
At Irish Bend in Lynn Co., Mastodon or Wolly Mamouth remains were observed by a fisherman falling out of the Willamette Silts. About 200 feet east a farmer collected Mastodon or Wolly Mamouth bones. at top of the Willamette Silts. The same person collected dozens of fist size or smaller erratics.. That person dragged several large erratics, with one up to 8.5 feet long, to an adjacent field. Water had to be deep enough, at roughly 275 ft. msl. elevation, for the ice to carry the large erratics to the southern valley, and temperature cold enough to prevent the ice from melting. A frozen Willamette River and flood plain water would have allowed Mastodon or Wolly Mamouth to travel far south in the Willamette Valley, walking on ice. This interpretation is consistent with research on Younger Drayas (about 12,900 to 11,600 yrs. B.P.), which ia a return to glacial condition. The Willamette River and flood waters were likely carrying a heavy suspended load under these conditions and deposited very fine sediment on flood plain that became the Malpass Stratigraphic unit.