This thesis describes an automated system for the analysis and description of patterns composed of straight line elements. It represents the second stage in the development of a system intended to aid archaeologists in tracing the evolution of decorative patterns found on pottery sherds. The samples provided by the Anthropology Department for this project are pottery rims excavated from sites at Penitas, Nayarit, Mexico. The input data are digitized pictures of photographs of the samples. The first phase of the system is image processing. A set of low level operators is employed to obtain as final output a pictorial and vector description of all line segments in the pattern. The second phase constructs a series of descriptions of the pattern, in which the successive steps reflect increasing levels of complexity in the interrelationships of the pattern elements. It first finds parallel and connected relationships between pairs of lines. The pairs are examined to obtain groups of equally-spaced parallel lines, and groups of lines connected at mutual endpoints, The groups are analyzed to yield the independent patterns which compose the picture, and the patterns are named in their left-to-right order.