Les loess de la vallée du Mississipi. Compte-rendu de l'excursion organisée par L. Follmer à l'occasion du Congrès de l'INQUA de 1987

Abstract

A synthesis on the loess of the Mississippi valley is proposed, based on both the study of the classical sections examined during the excursion and on the North American literature published on the subject. Results obtained from a few thin sections collected during the tour were also added. A precise stratigraphy exists for the loess of the upper Wisconsin although an agreement could not be reached on the correlation of events recorded during the lower Wisconsin and the Sangamon interglacial throughout the Mississippi valley. The stratigraphy of older loess is more imprecise. This stratigraphy is mostly based on paleosols which were studied from bulk samples. Molhsols occurred throughout the whole valley during the Wisconsinan period and were frequently reworked. Alfisols developed during the last interglacial period but were only eroded during the following glacial period. A tentative correlation with the European loess is proposed.