caliche

• 指干旱地区土壤下层由碳酸钙胶结形成的硬壳层或钙积层；也指甲乙智利和秘鲁硝石矿床中的硝酸盐矿石或砾石。

A noun referring to a hardened layer of subsoil encrusted with calcium carbonate, found in arid regions, or a nitrate-bearing rock or gravel from sodium nitrate deposits in Chile and Peru.

1. Hard subsoil crustC1formal

   A hardened layer of soil found in dry regions, often containing calcium carbonate.

   钙积层

   • Farmers in the desert struggled to break through the caliche layer.
   • The caliche made it difficult for plant roots to penetrate the ground.
   • Construction crews had to use special equipment to dig through the caliche.

   同义词hardpan

2. Nitrate-bearing depositC2formal

   A mineral deposit containing sodium nitrate, found in the deserts of Chile and Peru.

   硝石矿床

   • The caliche deposits in the Atacama Desert were a major source of nitrates.
   • Miners extracted caliche for use in fertilizers and explosives.
   • The region's economy once relied heavily on caliche mining.