Reformatted the description section on the upper part of the map. Format is set up in smaller paragraph columns for easier reading.
Brussels Hill in Door County, Wisconsin may be the erosional remnants of an asteroid impact crater. Unlike the generally horizontal Silurian sedimentary strata of the region, Brussels Hill consists of disturbed and deformed rocks which suggest this is the remains of an extraterrestrial impact structure. Evidence includes reported "megaclasts" up to 25 feet long that dip steeply at various angles (including vertical). These may be overturned and plastically deformed. Sandstone clasts up to 10 feet long have also been reported by Kluessendorf (see reference below). Cambrian sandstone generally lies 300 to 400 feet below the Silurian dolomitic limestone strata in the area. The sandstone clasts present at Brussels Hill may be explained by an impact event. Zawacki (below) reports no shatter cones in the limestone, though shock-metamorphic planar microstructures (PMs) were reported in the quartz grains of the sandstones. Brecciation occurs at many scales and there are reports of breccia-within-breccia occurrences which are indicative of impact structures (perhaps exclusively). Breccia dikes are common. The LiDAR image shows an unusual hummocky landscape which is typical of megabrecciation at impact sites. Look for carbonitic rocks with unusual vesicles, these may represent impact melt rocks. The erosional surface of Brussels Hill differs from hills of the surrounding area. The roughly-circular shape of the hill may support the impact hypothesis. Zawacki concludes that the hill is likely the eroded remnant of a central peak of a larger impact structure. References: Kluessendorf, Joanne, 2011, Geological Society of America Abstracts with Programs. Vol. 43, No. 1, p.117 Zawacki, Emily & Bjørnerud, M. (2015). A PREVIOUSLY UNRECOGNIZED IMPACT STRUCTURE AT BRUSSELS HILL, DOOR COUNTY, WISCONSIN: BRECCIATION AND SHOCK-METAMORPHIC FEATURES. 10.13140/RG.2.2.22564.88966.
Vendor: GIS Pro LLC
Primary Category: Professional
Secondary Categorization: Geological
Size: 40.5 MB
Maps purchased here can only be viewed in the Avenza Maps app on iOS and Android.
Get the app. Get the map. ®