Silurian carbonate outcrops within the southern part of the St. Ignace District of the Hiawatha National Forest (Mackinac County, Michigan) were examined to develop a local description of the exposed geology. The bedrock geology consists of the Manistique Group (dominantly the Cordell Formation) and the Engadine Group (Rockview Formation, Rapson Creek Formation, and Bush Bay Formation). Building on observations and differentiation from previous investigations, outcrops were selected to describe the macroscopic characteristics of these formations in attempt to develop a local description that would be more useful compared to confusing regional descriptions for researchers and forest officials. In Mackinac County, the Cordell Formation is a dark-to-light gray, chert-rich dolostone with abundant corals, stromataporoids, brachiopods, and echinoids. The Rockview Formation is a dark gray-to-white, chert-poor dolostone with microbiolite laminations, and brachiopod molds. The Rapson Creek Formation is a light gray-to-white, chert-free dolostone with abundant stromatoporoids. The Bush Bay Formation is light reddish brown to white in color, chert-poor, crystalline dolostone with abundant echinoids, brachiopods, and corals.

中文翻译：

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美国密歇根州上半岛麦基诺县 Hiawatha 国家森林内志留纪碳酸盐岩的露头和薄片尺度描述

检查了 Hiawatha 国家森林（密歇根州麦基诺县）圣伊格纳斯区南部的志留纪碳酸盐露头，以对暴露的地质进行局部描述。基岩地质包括 Manistique 组（主要是 Cordell 组）和 Engadine 组（Rockview 组、Rapson Creek 组和 Bush Bay 组）。基于与先前调查的观察和差异，选择露头来描述这些地层的宏观特征，以试图制定一个局部描述，与对研究人员和森林官员的混淆区域描述相比，这种描述更有用。在麦基诺县，Cordell 组是一种深至浅灰色、富含燧石的白云岩，含有丰富的珊瑚、层孔类动物、腕足类动物和海胆类动物。Rockview 组是一种深灰色至白色、贫燧石白云岩，带有微生物岩层和腕足动物模具。Rapson Creek 地层是一种浅灰至白色、不含燧石的白云岩，含有丰富的层孔体。布什湾地层呈浅红棕色至白色、贫燧石、结晶白云岩，含有丰富的海胆类、腕足类动物和珊瑚。