庆阳市属黄河中游内陆地区。
砒砂岩区是黄河中游集中的基岩产沙区，强烈的岩土侵蚀与砒砂岩的岩性密切相关。
The soft rock area is a major sediments-producing area resulting from bedrock erosion in the middle valley of the Yellow River.
黄河下游沉积泥沙主要来自黄河中游粗沙区，但至今粗沙区的范围及面积还未定论。
The sediment deposited in the lower Yellow River come mainly from the areas yielding coarse sands in the middle reaches of the river;
黄河下游沉积泥沙主要来自黄河中游粗沙区，但至今粗沙区的范围及面积还未定论。
The sediment deposited in the lower Yellow River come mainly from the areas yielding coarse sands in the middle reaches of the river;
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