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The Sinnipee Group is one of many Geological groups in Wisconsin's diverse landscape. Mostly it consists of Sedimentary carbonate rocks. Primarily made of dolostone, it also has limestone as a secondary component and can even have shale imbedded with it. It was formed in the Ordovician and has three rock members in it. These members are the Galena, Decorah, and Platteville Formations.〔(【引用サイトリンク】 title=Sinnipee Group )〕 ==Formations== The platteville limestone is one of the formations of the Sinnipee Group. It is primarily made of limestone. It lies over the Glenwood Shale. In many places, the platteville limestone has dolomitic mottles. This member is heavily jointed and the mottles happened before the jointing. This particular member is being quarried heavily. While not as full as the Decorah Shale, the platteville limestone is a large layer that has bryozoans, brachiopods, clams, snails, cephalopods, and trilobites that can be found in the limestone sediments. The platteville limestone is easily seen along the roads following the Mississippi River due to erosion. The Decorah Shale is another formation of the Sinnipee Group. It is primarily made of fossiliferous shale. It lies on top of the platteville limestone formed by the shallow sea that covered central North America. Because of its chemistry it tends to erode rapidly. Since the Decorah Shale is fossiliferous the Decorah Shale layer is often used as a place for amateur fossil hunters to begin their collections. It also serves as release of PO4 into the ground water system if acid rain is introduced to it. This allows, in some cases, for new minerals. The Decorah Shale formation is made of three members. These members are the Spects Ferry, a geological an argillaceous limestone,〔(【引用サイトリンク】 title=Geologic Unit: Spects Ferry )〕 argillaceous dolomite,〔(【引用サイトリンク】 title=Geologic Unit: Guttenberg )〕 Calcareous shale and argillaceous limestones.〔(【引用サイトリンク】 title=Geologic Unit: Ion )〕 The Galena Group is also a formation of the Sinnipee Group. It is primarily made of Limestone and is deposited on the Decorah Shale. The Galena Group is considered fossiliferous. It is believed that the Galena Group was deposited in a calm marine environment. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sinnipee Group」の詳細全文を読む スポンサード リンク
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