Prepare a research paper on the various methods of depreciation. Your research should include:

1. An analysis of why depreciation is an allocation process and not valuation process.
2. A description of the following depreciation methods:
   1. ACRS
   2. MACRS
   3. traight-line depreciation.
3. An explanation of the how cost recovery is different for natural resources.
4. An explanation of why there could be a difference between the depreciation amount on a companys book (book depreciation) and the depreciation amount on a companys tax return (tax depreciation).