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highly glauconitic and contains abundant dolomitic intraclasts. The Lone Rock Formation is about 100 feet thick (30 meters) thick. The basal Birkmose Member is about 20 feet (6 meters) thick and the overlying Tomah Member is less than 10 to 15 feet (3 to 4.5 meters) thick. Most of the Lone Rock Formation in Sherburne County consists of the uppermost Reno Member” (1).  Cw – Wonewoc Sandstone (Upper Cambrian) – “This unit, formerly referred to as the Ironton-Galesville Sandstone, is composed mostly of fine- to coarse-grained, moderately to well sorted, light gray to yellowish-gray, quartz sandstone. The upper part is the coarsest-grained; the lower part is finer-grained, better sorted, and progressively finer-grained toward its base. Thin shale and siltstone beds are present throughout the formation but are more common in the lower part. The very fine- grained sandstone in the lower part is feldspathic. The sandstone contains abundant linguliform brachiopod valves locally along bedding planes. The thickness of the formation is 50 to 60 feet (15 to 18 meters). The Wonewoc Sandstone is conformable with overlying and underlying formations; however, there is a subtle internal unconformity marked by a pebbly sandstone layer observed in outcrop and cores elsewhere.” “However, it is not possible to recognize the unconformity in well cuttings or geophysical logs” (1).  Ce – Eau Claire Formation (Middle and Upper Cambrian) – “The formation is composed of yellowish-gray to pale olive-gray, very fine-grained, feldspathic sandstone, siltstone, and shale. The upper part is predominantly shale and siltstone, the lower part predominantly glauconitic sandstone and siltstone.” “It contains linguliform brachiopod shells. The formation ranges from 70 to 80 feet (21 to 24 meters) in thickness. The contact with the underlying Mt. Simon Sandstone is conformable and transitional. Siltstone and shale beds of the Eau Claire Formation are commonly interbedded with medium- to coarse-grained quartzose sandstone of the Mt. Simon Sandstone” (1).  Faults, Paleozoic rocks – “interpreted to have had dip-slip movement. Letters indicate relative vertical displacement: U-up, D-down. Faults are concealed by Quaternary sediments and recent alluvium and are inferred from subsurface geologic data supplemented by aeromagnetic and gravity data. Offsets of Paleozoic strata indicate that these faults were rejuvenated during post-Mesoproterozoic time. Faults in Precambrian (Mesoproterozoic, Paleoproterozoic, and Archean) rocks inferred from geophysical data” (1). 1 University of Minnesota’s Digital Conservancy. C-32 Geologic Atlas of Sherburne County, Minnesota. Lusardi, Barbara A. (2013). Accessed December 4th, 2024. Retrieved from: https://hdl.handle.net/11299/159393