Nothing is stopping the magma from seeping even deeper into the sandy subsoil.

没有东西可以防止岩浆继续向下渗透到沙质底土。

Do you know why the soil is so much darker in colour than the subsoil and the rock beneath it?

你知道吗, 土壤的颜色为什么比底土及其下方的岩石深那么多?

At one time the soil was just like the subsoil, and before that it formed part of some hard and solid rock.

曾几何时, 土壤与底土一样结实, 再前追溯的话, 它还曾经坚硬、结实的岩石。

But the real treasures are non-financial assets—buildings, land, subsoil resources—which the IMF believes are worth three-quarters of GDP on average in rich economies: $35 trillion across the OECD.

但这还算不上真正值钱的，真正值钱的那些非金融性资产，也产，土地和地下资源。据国际货币基金组织测算，这部分家底的价值在35万亿美元左右，相当于富国平常年份GDP总和的四分之三。

He then moves on to a subterranean walking tour of the city, indicating the location of rock and water below the subsoil, before taking the reader back to the surface.

然后， 他继续进行城市的地下徒步旅行，指出地下岩石和水的位置，然后再将读者带回地面。

In some places the workmen may have to dig down only a few feet before they reach the rock, but in other places both the soil and the subsoil may be many feet deep.

有时候, 工人们可能只需挖掘几英尺便能看到岩石层；不过另外一些时候, 岩石层上方的土壤与底土可能达到很多英尺之厚。