Architectural Geology of Chicago’s Suburbs

These photos are all copyright 2022 by Raymond Wiggers. For permission for one-time use, please contact me at



Chales Dawes House

The Dawes House, now home to the Evanston History Center , is an example of the French Chateau style that incorpates in its base and door surround the “Portage Red” variety of the Jacobsville Sandstone. It was quarried near Portage Entry, on Michigan’s Keweenaw Peninsula. In common with all other Lake Superior Brownstone types, its exact age has not been pinned down because it lacks datable fossils and other indicators that geochronologists could use. However, we know it formed from sand deposited in the Midcontinent Rift that while still active in the late Mesoproterozoic, had nearly torn Laurentia, North America’s forerunner, apart. Itself conceivably as young as Cambrian, the Jacobsville is most likely to be early Neoproterozoic instead.

The current terra-cotta roofing tiles, which date from the 1980s, were manufactured by the same renowned Ludowici Company that had made the original set. The source of the ocher-colored bricks is unknown, but they do closely resemble in color and their iron-spotted patterns a popular type made in St. Louis.

The current

Above the red Jacobsville Sandstone, and making up most of the house’s evaltions, is the unsourced ocher and iron-flecked brick laid in the Flemish Bond pattern. Here stretchers (bricks set lengthwise) alternate with headers centered on the middle of the stretchers of the courses immediately above and below.

As sandstone weathers, as the Jacobsville has in places on the side of the Dawes House, it can form a honeycombed or scooped-out appearance. Geologists call this pattern “tafoni”.

Lake Forest

Hotchkiss Hall, Lake Forest College

Detail of the striking Lake Superior Brownstone exterior of Hotchkiss Hall, one example of the Richardsonian Romanesque style on the campus of Lake Forest College. Crossbedding, excellent geologic evidence that the original sand was deposited in a flowing stream, is clearly visible in the center, irregularly shaped block. This rock type, which probably dates to the Neoproterozoic era, is quarried both in northernmost Wisconsin (Chequamegon and Orienta Sandstones) and in Michigan’s Upper Peninsula (Jacobsville Sandstone).



Cladding of the 3.52 Ga Morton Gneiss (“Rainbow Granite”) on the exterior of an otherwise undistinguished bank building on Ridge Road. Some effort was made here to mount the panels so that the wavy foliation of this ancient metamorphic rock was oriented more or less vertically.


St. Charles

Municipal Center

The Municipal Center of St. Charles, on the bank of the Fox River, is a famous example of Art Moderne architecture. It is clad in the “Cherokee” variety of Georgia’s Murphy Marble.

Hotel Baker

The Spanish Baroque comes to Illinois’ Fox River Valley: detail of the flamboyant terra-cotta entrance of Hotel Baker. This demonstrates the great technical proficiency of the artisans of the American Terra Cotta Corporation.


Young House

Oswego’s Young House, as it appeared ca. 1910. Its ground story is sheathed in locally collected river-bed or fieldstone boulders – locally known as “hardheads.” (Photo by Dwight Young; courtesy of the Little White School Museum, Oswego, Illinois)