The upper part of the 'pipe', where it had been most exposed to weathering, was soft  and crumbly, and was known as 'yellow ground', and it could be easily excavated by hand.

“管道” 的上部，最容易受到风化的地方，柔软而易碎， 被称为“黄地”，很容易用手挖掘。

Not only had the market been flooded, but also the soft 'yellow ground' had been mostly  exhausted, giving way to harder 'blue ground' which had to be broken with machinery or dynamite.

不仅市场被淹没，而且柔软的“黄地” 已经大部分被耗尽，取而代之的是坚硬的“蓝地” ，必须用机械或炸药来破坏。

The 'yellow ground' had to be smashed up with picks so that  it could be coarsely sieved in large wire frames, and the resulting large pieces removed by  buckets to be further sieved and scraped.

必须用镐将“黄土” 打碎，以便可以在大型金属丝框架中进行粗筛，然后将所得的大块用桶移走， 以便进一步筛分和刮擦。