中南阿拉斯加的岩土和化石

Rocks,loess and fossils of Southcentral Alaska

每个地区的岩土和化石都能反应当地地质年代的变化,确定地层的年代等。文章在梳理岩石的类别以及黄土概念的基础上,对阿拉斯加中南部地区的岩土和化石情况进行了说明,指出:(1)中南阿拉斯加的岩石种类丰富,绝大部分基岩起源于各地体向北美克拉通贴附时隆起的海相沉积物;(2)马塔努斯卡河谷地区黄土层土壤十分肥沃,主要是由楚加奇山吹出的强风将附近冰川上的泥沙颗粒搬运到马塔努斯卡河谷的帕尔默周边地区后沉积下来形成的;(3)在中南阿拉斯加只发现了两处恐龙化石并且第三纪哺乳动物的化石和更新世的大型已灭绝的动物化石都很罕见。

Rocks, loess and fossils can response the local geological changes. Studying them is benefit to understand the morphogenesis of Southcentral Alaska. This paper explains the situation of rocks, loess and fossils in Southcentral Alaska on the basis of combing the category of the rock and the loess concept under the premise of knowledge. It points out： （1）There are abundant rock types in Southcentral Alaska. Most of the bedrock of Southcentral Alaska originated as marine sediments that were uplifted when terranes accreted onto the continent. （2）Soil that develops on a loess layer is particularly fertile Matanuska Valley. The landscape around Palmer in the Matanuska Valley has thick layers of loess that have accumulated as strong winds blow out of the Chugach Mountains carrying particles of silt off nearby glaciers. （3）Only two dinosaur fossils have been located in Southcentral Alaska. Tertiary mammal fossils and the fossils of large, extinct Pleistocene mammals are a rarity.