Written land descriptions may be based on the rectangular survey system (also known as the township and range system), a metes and bound description or a coordinate description system. This system is based on the idea of parallels and meridians that circle the globe. The equator and all horizontal lines north and south of it are known as parallels. The vertical lines which converge at the north and south poles are known as meridians.
The rectangular survey
system also has its own special meridians and parallels throughout the
United States. The meridians are known as "principal" meridians.
Each principal meridian has a parallel which goes with it.
These are known as "base" lines. The points where these two meet are
known as initial points. In Oklahoma, land described using this
system is referenced to either the Indian or the Cimarron Meridians.
Another set of lines
is established at 24 mile intervals north and south of the base line and
at 24 mile intervals east and west of the principal meridian. The
east-west lines are called standard parallels or corrections lines.
They are one continuous, uninterrupted line. The north and south
lines, called guide meridians, are not continuous throughout their
length. Because meridians converge as they get closer to the poles,
they must be broken at the base line and at each standard
Sections can be subdivided as well. The quarter section (160 Acres, 1/2 mile square), the half-quarter or eighth sections (80 Acres, 1/4 mile by 1/2 mile), and the quarter-quarter or sixteenth section (40 Acres, 1/4 mile by 1/4 mile). The quarter-quarter section is the minimum legal subdivision under the general land laws but it is common to divide the subdivision further for descriptive purposes.
Graphic land descriptions are based on the recording or filing of maps. These descriptions are known as "recorded map descriptions" or "legally recorded plats". Record map descriptions are descriptions of parcels by reference to lot numbers (or letters) and/or block numbers (or letters), and name or numerical designation given to a recorded or filed map.
The County Assessor's office also uses aerial photographs to locate and identify property. There are several types of aerial photographs as listed below: