Sugar Run Dolomite

The Sugar Run Dolomite is a geologic formation in Illinois. It is a finely-bedded dolomite, preserving fossils dating back to the Silurian period. This formation is named for the Sugar Run stream in Joliet, along which it is well exposed. The dolomite is off-white/grey on freshly cut surfaces but over time oxidizes to a distinctive cream yellow color due to trace presence of iron. It is a member of the Niagaran series.^[1]

Sugar Run Dolomite
Stratigraphic range: Silurian
Chicago's Holy Name Cathedral, made of Sugar Run Dolomite, aka "Athens marble" or "Lemont limestone"
Type	Formation
Lithology
Primary	dolomite
Location
Region	Illinois
Country	United States
Type section
Named for	Sugar Run Stream

Use in architecture

This formation has been quarried for building material since the mid-19th century, sometimes sold under the misleading trade name of "Athens marble". It is also known as Joliet or Lemont limestone.^[2] It was used widely in the construction of many Chicago homes and buildings from the 1850s-1880s, including the famous Chicago Water Tower. By the 1890s, it fell out of fashion as a building material in favor of more durable Indiana limestone.

See also

• Earth sciences portal
• Illinois portal
• Paleontology portal

• List of fossiliferous stratigraphic units in Illinois
• Lannon stone