Jungle Mystery Number One

This is the Teman Negara, a jungle rainforest deep within peninsular Malaysia, and the location of a number of mysteries for me.

The first Jungle Mystery is this: Teman Negara is not just a rainforest, it is a primary rainforest: the wettest and the hottest that they get.  It is also the world’s oldest rainforest, more than 100 million years old.

Now here comes the mystery: if the jungle is so wet and you can see the tremendous silt being carried in the river – and if the jungle is so old – then how can the jungle still be there?  Shouldn’t the rains have washed away all the mud and soil long, long ago?

Or does this perhaps mean the rate at which new soil is created (for example, from dying vegetation) exceeds the rate that silt is carried away in the river?