Date of Award


Degree Name

Master of Arts


Geological and Environmental Sciences

Access Setting

Masters Thesis-Open Access


There are numerous linear features in Alpena and Presque Isle Counties, Michigan, which are generally visible on aerial photographs. These photolinears trend in two general directions, northeast-southwest and northwest-southeast. These two sets are perpendicular to each other, and represent vector means of two fracture sets.

The development of the photolinears began in Early Devonian. Throughout its history, ground water flowed along underground channels connecting fracture intersections. This underground drainage network is responsible for many of the photolinears. Some of the photolinears can be attributed tb Early Devonian ground water activity and subsequent collapse of the Salina Salt basin, and some are attributable to more recent ground water activity.

Some photolinears are the result of differential erosional resistance between different beds of rock, or the result of progressive stages of Pleistocene lakes.