Answer:
thick vegetation
Step-by-step explanation:
The felling of trees and the destruction of vegetation in areas close to river banks may be accelerating the occurrence in Amazonas of the natural phenomenon known as 'fallen lands', which is the detachment of soil from river banks. The Geological Survey of Brazil (CPRM) estimates that all municipalities bordering the rivers of the watershed in the state are affected by the phenomenon, especially in the period of ebb. Although natural, the phenomenon is a risk to riverside populations.