Late Wisconsin History North of the Giants Range, Northern Minnesota, Inferred from Complex Stratigraphy

• Published in: Quaternary Research
• Main Author: Björck, Svante
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1990
• Subjects: Glacial Lake; St. Louis; Parkland; Tundra
• Online Access: http://dx.doi.org/10.1016/0033-5894(90)90082-v; http://api.elsevier.com/content/article/PII:003358949090082V?httpAccept=text/xml; http://api.elsevier.com/content/article/PII:003358949090082V?httpAccept=text/plain; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400020391

Abstract In an area north of the Giants Range in northeastern Minnesota the late Wisconsin glacial and extraglacial lithostratigraphy shows that, apart from one occurrence of red clayey till, the deposits can be related to the deglaciation of the Rainy Lobe, the margin of which retreated northward, leaving debris-rich ice behind. By a combination of pollen stratigraphy, lithostratigraphy, and chronostratigraphy of lake sediments in this area, together with multivariate numerical analyses of the data set, a “hiatus” stratigraphy was set up. Combined with the glacial and extraglacial stratigraphy, it shows that the area of Glacial Lake Norwood was possibly later filled with sediments, between masses of stagnant ice, following a damming of drainge in the south by the St. Louis Sublobe. The area was drained through the Embarrass channel when the St. Louis Sublobe retreated. Then followed the drainage of Lake Koochiching through the Embarrass channel. At ca. 10,200 14 C yr B.P. the area apparently became free of stagnant ice as normal lake sedimentation began in all lakes studied. A lake-level rise is indicated ca. 1000 yr later. Apart from a long-lasting phase of birch tundra parkland between ca. 12,000 (or 11,500?) and 10,600 14 C yr B.P., the general pollen stratigraphy fits into the regional picture with a more or less undisturbed and gradual plant immigration from the time of the culmination of the St. Louis Sublobe.