Left image group: Initial Site Investigation: Aeromagnetic Studies Of Minnesota - Geophysical Evidence of a Deeply Buried Proterozoic Rift System Passing Beneath Minneapolis.

Left Image: Shaded-relief Aeromagnetic Map of Minnesota, Minnesota Geologic Survey State Map Series, S-18, Modified from Chandler, V. W., 1991; concentric red rings on image: 25 mi., 50 mi., 100 mi., radius from Minneapolis.

Right/Top Image: Generalized cross-section of the Mid continent Rift System (after Gibson, 1979) in the Lake Superior area. Numbers refer to densities in g/cm3. Adapted from "The Role of Rifting in the Tectonic Development of the Mid continent, USA," G. R. Keller, E. D.Lidiak, W. J. Hinze and L. W. Braile, Tectonophysics, 94 (1983), 391-412.

Right/Bottom Image: Generalized map of the Mid continent Rift System of North America, after Craddock, 1972, Halls, 1978, and Hinze and Wold, 1982. From "Geologic and Geochemical Evidence for the Nature and Development of the Middle Proterozoic (Keweenwan) Mid-continent Rift of North America," John C. Green, Tectonophysics, 94 (1983), 413-437.

Center: Initial Site Studies:UMN-Rapson Site Elevation (Surface to Mantle)

Section beneath Rapson Hall reveals Proterozoic volcanics, as inspiration for Inversion2: Dark Matter (Proterozoic/Holocene) I and II, and an extension of the rift system exposed as anorthositic gabbro at the Mesabi Black quarry in northern, MN, where material was excavated for SITE INDEX.

QUATERNARY:
35 feet Quaternary terrace sand, gravelly sand, silty sand
25 feet thickover 10 feet of till.

ORDOVICIAN:
5 feet Decorah Shale (mostly eroded):
30 feet Platteville Formation: Limestone and dolostone.
5 feet Glenwood Formation: Shale and sandstone.
165 feet St. Peter Sandstone: Fine- to medium grained sandstone with minor shale and siltstone.
125 feet Prairie du Chien Group: Dolostone and minor sandstone.

UPPER CAMBRIAN:
100 feet Jordan Sandstone: Fine-, medium- and coarse-grained sandstone.
40 feet St. Lawrence Formation: Dolomitic siltstone.
140 feet Franconia Formation: Very fine- to fine sandstone and siltstone,glauconitic.
65 feet Ironton and Galesville Sandstone: Fine- to medium grained sandstone.
95 feet Eau Claire Formation: Siltstone, shale, very-fine grained sandstone.
260 feet Mt. Simon Sandstone: Fine- to coarse-grained sandstone, minor shale

.MIDDLE PROTEROZOIC:
2.7 - 4 km Solor Church Formation: Red-brown shale and lithic sandstone. (8860 -13125 feet)
About 3 km Mid Proterozoic volcanic rock. (9800 feet)
1065 feet to the base of the Paleozoic formations
9925 to 14190 feet to the base of the Solar Church Formation.

Data supplied by:
John Mossler, Minnesota Geological Survey

Right image group: Initial Site Studies: Geologic Analysis of UMN Campus and Selected Buildings

Top Left Image: Civil Engineering Complex: Holocene structure of varied composition with 1-7 floor penetration into Quaternary and Paleozoic sediments: Building: Brick - local altered Paleozoic sediment. Site: differentiated glacial till - Quaternary; Decorah Shale - Ordovician; Platteville Formation - Ordovician; St. Peter Sandstone - Ordovician; Parie du Chien Group - Ordovician.

Top Center Image: College of Architecture and Landscape Architecture;
Holocene structure of varied composition resting on Quaternary sediments with shallow penetration. Original building: Brick - local altered Paleozoic sediment; New Addition: Concrete - local altered Cambrian sediment; Copper Sheathing - Chilean altered metamorphic rock; Site: same as adjacent Civil Engineering Complex.

Top Right Image: Pillsbury Hall: Geology Department Holocene structure of primarily Proterozoic sediments resting on Quaternary sediments with shallow penetration. Building: Fond du Lac and Hinckley sandstone: Keweenawan Supergroup, late Proterozoic Era, Northern MN. Site: same as adjacent Civil Engineering Complex.

Bottom Image: Mississippi River section (looking east): Holocene structures (UMN campus) above late Cenozoic glacial sediments and Paleozoic marine sediments (see Civil Eng. Complex, above).