Not many rainforests and the rest is just built up area. Suburban areas.

雨林地区并不多，其他地方就是建筑物密集区。郊区等等。

Marine heat waves are caused by ocean currents building up areas of warm water.

海洋热浪是由洋流形成的温暖水域引起的。

However, because they found the bones far in the ground beneath a built up area, they couldn't excavate to find anymore.

然而，由于他们在建筑区下方的地下很远的地方发现了这些骨头，所以他们无法再挖掘了。