Heituhu formation is gray and gray-black silty clay with limnological facies in early and middle period of Holocene, and bearing lots of spiral case;

黑土湖组为全新世早—中期湖沼相沉积的灰—灰黑色粘土类粉砂质粘土，含大量淡水螺蚌介壳；

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Heituhu formation is gray and gray-black silty clay with limnological facies in early and middle period of Holocene, and bearing lots of spiral case;

黑土湖组为全新世早—中期湖沼相沉积的灰—灰黑色粘土类粉砂质粘土，含大量淡水螺蚌介壳；

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