1. LIDAR images show that thousands of years ago the Amazon had thousands more human settlements than it does today; that it once held a large population.
2. Many of the locations of the Amazonian “dark soil” correspond to where LIDAR (ground penetrating radar) images show outlines of ancient human settlement.
Graham Hancock takes the position that a very, very (during the last ice age) ancient civilization in the Amazon river basin created the black soil.
LIDAR and RADAR, are not the same thing.
Within the context of mapping the remains of ancient civilizans ...
LIght Detection And Ranging uses coherent visible or near infrared radiation to map the ground surface at very high precision. The Source is a LASER.
Ground Penetrating RADAR (RAdio Detection And Ranging) uses microwave radiation to map objects and structures under the ground surface which differ in absorption or reflection from the overall ground material.
They are similar and complementary technologies, not the same.
I read all the way to the last comment, and nowhere did anyone mention the writings of a Spanish member of the conquest of the Inca who traveled down the Amazon to the Atlantic coast. He was quite impressed by the amount of civilization he found along the shores. No doubt he and his crew were generous in their distribution of new and deadly germs to the welcoming population which soon after ceased to exist.
Is it also possible that occasional volcanic eruptions sent burned waste and ash down the river which were collected and added to the shore soil?