Publication: $0.50 (2 p.,
8.5 x 11 inches), ES51
Large poster: $25.00
(35 x 46 inches),
Small poster: $12.00
(17.5 x 23 inches),
Order form (PDF)
DOWNLOAD page-size version (PDF)
Underneath soil and glacial deposits, or in some places at the Earth’s surface, rocks are found in stratified layers. It’s common knowledge that these rocks have names such as limestone, sandstone, and so forth. But geologists also classify rocks that have similar characteristics into named stratigraphic units; the major categories are groups, which can be further broken down into formations, which can be subcategorized into members. Not all rock units, however, can be conveniently categorized this way; for example, not every formation belongs to an overarching group, and all formations do not have member subdivisions.
The statigraphic profile shows these named categories of Wisconsin bedrock as well as age-related information and rock type. Based on a 1968 publication by former Survey director M.E. Ostrom, this version reflects the results of the ongoing research and current thinking about the Precambrian and Paleozoic rock in Wisconsin—the rocks that date from 2,800 million to 359 million years ago.
Not too surprisingly, compressing 2,500 million years of history onto a single sheet requires a fairly complex graphic. The page-size version explains on the reverse side how to read and interpret the information embedded in the stratigraphic profile.