事实上，灰化石遗址（Gray Fossil Site）里犬齿猫科动物、骆驼、大象和犀牛的骨头表明这些动物生活于400多万年前的志愿者州（Volunteer State，即田纳西州）。

In fact, at the Gray Fossil Site, bones from a saber-toothed cat, camel, elephant and rhinoceros indicate these animals lived in the Volunteer State more than 4 million years ago.

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不可渗透的粘土限制了水和黄腐酸的向下渗透，从而减少了化学风化和土壤灰化作用。

Impermeable clay limits downward percolation of water and fulvic acids, reducing chemical weathering and podzolization.

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关于中国灰化土的分类，特别是与美国灰化土分类的对比问题，目前国内外均存在分歧，这项研究尚有待深入进行。

There are some divergences of views on the classification of podzolic soils among in China and other countries and much work remains to be done in this respect.

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