What does topography mean?

topography is a detailed map of the surface features of land

Topography is the study of the shape and features of land surfaces. The topography of an area could refer to the surface shapes and features themselves, or a description (especially their depiction in maps).

Explanation:

Topography is a field of geoscience and planetary science and is concerned with local detail in general, including not only relief but also natural and artificial features, and even local history and culture. This meaning is less common in the United States, where topographic maps with elevation contours have made "topography" synonymous with relief.

Hope I helped.

the thirteen colonies are:

connecticut, delaware, georgia, maryland, massachusetts, new jersey, new york, new hampshire, north carolina, pennsylvania, rhode island, south carolina, virginia

81 is a composite number.