ABSTRACT

The type of cross-lamination most commonly observed in the Upper Cambrian Franconia Formation of southwestern Wisconsin is trough cross-lamination. Statistical analyses of 1023 cross-lamination dip azimuths in the sandstone members of the Franconia Formation indicate a preferred orientation of sedimentary transport 151 degrees to the southeast. The mean dip of the individual cross-laminae in 700 measurements is 18 degrees. A comparison of sand size of individual cross-laminae with degree of dip indicates that an increase in dip is associated with good sorting and coarser grain size.

The Precambrian upland to the north of the area (or strata in equivalent position) is believed to have supplied sediments to the Franconia seas. Cross-lamination (azimuth) study of the Precambrian Baraboo Quartzite within the area also reflects this northerly source. Similar evidence obtained from regional studies of Huronian and Upper Cambrian sediments indicates the possibility of a stable regional paleoslope throughout a substantial period of geologic time.