When natural resources have their value reduced to zero they are written off.
An asset write-off removes an asset's cost off the balance sheet and expenses it on the income statement.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"Green River Natural Resources Area - observation tower 01."
http://commons.wikimedia.org/wiki/File:Green_River_Natural_Resources_Area_-_observation_tower_01.jpg
Wikimedia
CC BY-SA.
