Brussels Hill in southern Door County, Wisconsin, is a localized area of faulted and brecciated bedrock in a region of otherwise undeformed lower Silurian dolostone that has been tentatively interpreted as an impact crater. The area of disturbed rock coincides with a nearly circular, 2-km-wide, flat-topped hill that stands about 40 m above the surrounding landscape. Glacial till and polished, striated surfaces on the brecciated bedrock indicate that the disturbance predated the last ice advance and suggest that the hill may have been even higher before glaciation. Anomalous, apparently intrusive bodies of glauconite-bearing sandstone within the brecciated dolostone were likely derived from Cambrian strata, which are normally 400 m in the subsurface in the area. A 103-m drill core into the center of the disturbance recovered 70 m of brecciated dolostone and shale, much of it vesicular, but with no features diagnostic of shock metamorphism. The lowest 33 m of the core sampled the upper Ordovician Maquoketa Formation, which appeared to be subhorizontal and only locally disrupted. This is puzzling, given that material from greater depth must have been brought up through this level. The fact that an area of such fragmented rock stands as a topographic high is also hard to explain. Brussels Hill may have been the site of supersonic impact, but an endogenous process such as violent fragmentation in the upper part of a diatreme cannot be ruled out.

中文翻译：

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威斯康星州多尔县布鲁塞尔山：受扰基岩的神秘区域

位于威斯康星州多尔县南部的布鲁塞尔山是一个局部区域，位于一个未变形的下志留系白云岩地区，该地区暂时被解释为一个撞击坑。受扰动的岩石区域与位于周围景观上方约 40 m 的近圆形、2 公里宽的平顶山重合。角砾岩基岩上的冰川和抛光的条纹表面表明扰动早于最后一次冰推进，并表明该山可能在冰川作用之前更高。角砾状白云岩中异常的、明显侵入的含海绿石的砂岩体很可能来自寒武纪地层，该地层通常位于该地区的地下 400 m。钻入扰动中心的 103 米钻芯回收了 70 米角砾状白云岩和页岩，其中大部分是水泡状的，但没有可诊断出冲击变质作用的特征。岩心的最低 33 m 采样了上奥陶统 Maquoketa 组，该组似乎是亚水平的，只是局部中断。这是令人费解的，因为来自更深处的材料一定是通过这一层提出的。如此破碎的岩石区域位于地形高度这一事实也难以解释。布鲁塞尔山可能是超音速撞击的地点，但不能排除内源性过程，例如在直径的上部剧烈破碎。岩心的最低 33 m 采样了上奥陶统 Maquoketa 组，该组似乎是亚水平的并且只是局部破坏。这是令人费解的，因为来自更深处的材料一定是通过这一层提出的。如此破碎的岩石区域位于地形高度这一事实也难以解释。布鲁塞尔山可能是超音速撞击的地点，但不能排除内源性过程，例如在直径的上部剧烈破碎。岩心的最低 33 m 采样了上奥陶统 Maquoketa 组，该组似乎是亚水平的并且只是局部破坏。这是令人费解的，因为来自更深处的材料一定是通过这一层提出的。如此破碎的岩石区域位于地形高度这一事实也难以解释。布鲁塞尔山可能是超音速撞击的地点，但不能排除内源性过程，例如在直径的上部剧烈破碎。