The major categories of property and equipment and related accumulated depletion, depreciation, amortization and impairment as of September 30, 2011 and December 31, 2010 are as follows:

Included in oil and natural gas properties at September 30, 2011 is the cumulative capitalization of $22,252,000 in general and administrative costs incurred and capitalized to the full cost pool. General and administrative costs capitalized to the full cost pool represent management's estimate of costs incurred directly related to exploration and development activities such as geological and other administrative costs associated with overseeing the exploration and development activities. All general and administrative costs not directly associated with exploration and development activities were charged to expense as they were incurred. Capitalized general and administrative costs were approximately $1,338,000 and $4,126,000 for the three months and nine months ended September 30, 2011, respectively, and $1,044,000 and $3,015,000 for the three months and nine months ended September 30, 2010, respectively.

At September 30, 2011, approximately $5,708,000 of oil and gas properties related to the Company's Belize properties is excluded from amortization as they relate to non-producing properties. In addition, approximately $10,349,000 of non-producing leasehold costs resulting from the Company's acquisition of West Texas Permian properties, $302,000 of non-producing leasehold costs related to the Company's Bakken properties and $4,342,000 of non-producing leasehold costs related to the Company's Colorado properties are excluded from amortization at September 30, 2011. Approximately $1,088,000 of non-producing leasehold costs related to the Company's Southern Louisiana assets, $86,855,000 of non-producing leasehold costs related to the Company's Ohio leasehold costs and $34,000 of non-producing leasehold costs related to other projects are also excluded from amortization at September 30, 2011.

The Company evaluates the costs excluded from its amortization calculation at least annually. Subject to industry conditions and the level of the Company's activities, the inclusion of most of the above referenced costs into the Company's amortization calculation is expected to occur within three to five years.

A reconciliation of the asset retirement obligation for the nine months ended September 30, 2011 and 2010 is as follows: