Although there are numerous publications on the geology of high-grade gneiss terrains, few descriptions exist of how to map and carry out structural analysis in these terrains. Textbooks on structural geology concentrate on technIques appli cable to low-grade terrains. Geologists who have no experience of mapping high-grade gneisses are often at a loss as to how to apply techniques to high grade rocks that were developed for low to medium grade metamorphic terrains. Any study of deep crustal processes and their development through time should begin with examination of the primary data source...