We are very familiar with topographic contours of landforms. Since landforms are complex surfaces, topographic contours (and bathymetric contours below water level) follow contorted paths tracing out a horizontal line on the map. It is often convenient to imagine oneself “walking out contours” and so visualize the land surface and its slopes. The closer contours are spaced, the steeper the surface. Occasionally contours merge, one above the other, where a cliff is located.

Geologists have long maintained that their discipline differs strikingly from chemistry and physics in being historical. There has been almost no explicit consideration by geologists, however, of the particular methodological problems imposed by the historical dimension. Historians and philosophers, on the other hand, have considered the problems of historical method at great length, and in recent years there has been, it seems, an increased interest in the methodology and philosophy of history. It is my purpose here to consider the extent to whieh the issues raised in recent discussions of explanation in human history are pertinent to the problem of explanation in historical geology. Because paleontology presents special methodological problems that I shall later discuss in detail (see pp. 148-70), Ihave omitted at this point any consideration of geological explanations containing paleontological concepts. <...>

The Gull Rapids area, Manitoba, lies on the Superior craton margin and forms part of the Superior Boundary Zone (SBZ), a major collisional zone between the Archean Superior craton and the adjacent Paleoproterozoic Trans-Hudson Orogen. There are two main rock assemblages at Gull Rapids: orthogneisses (of possible Split Lake Block origin) and supracrustal rocks (metavolcanic and metasedimentary). Late, crosscutting felsic and mafic intrusive bodies (mostly dykes and sills) are used to constrain the relative and absolute timing of deformation and metamorphism. 

Deformation of the Assegaai supracrustals and adjoining granitoids, Transvaal, South Africa
Suprastructure/infrastructure transition, east-central Cariboo Mountains, British Columbia: geometry, kinematics and tectonic implications
Strain and deformation mechanisms in the Variscan nappes of Vendee, South Brittany, France
The Najd fault system revisited; a two-way strike-slip orogen in the Saudi Arabian Shield
Artificial generation of pseudotachylyte using friction welding apparatus: simulation of melting on a fault plane
Tectonics of the Thingvellir fissure swarm, SW Iceland
Fracture propagation associated with dike emplacement at the Skaergaard intrusion, East Greenland

Implications of mylonitic microstructures for the geotectonic evolution of the Median Tectonic Line, central Japan
Structures and fabrics in a crustal-scale shear zone, Betic Cordillera, SE Spain
Strain and displacement across the Pinalefio Mountains shear zone, Arizona, U.S.A.
Sense of shear and displacement estimates in the Abeibara-Rarhous late Pan-African shear zone, Adrar des Iforas, Mali

Interest in the plastic deformation of rocks arises mainly from its application in the Earth sciences, especially in structural geology and tectonics. Its experimental study has consequently been pursued mainly in laboratories associated with geology or geophysics departments or institutes. However, the physical mechanisms involved are of considerable interest in materials science and some workers in the field of rock deformation have had a materials science affiliation.

The origins of balanced sections lie in the petroleum industry in the 1950's and 19601s, most obviously in Calgary, Canada. The first published balanced sections are those by Bally, Gordy and Stewart 119661 of the Canadian Rockies. The concepts of thrust-terrain structural styles, upon which they are based, have been developing since Peach and Horne's [I9071 classic work on the Moine thrust zone in Scotland. To begin, how can we define a "balanced" section?

Footwall geometry and the rheoiogy of thrust sheets
Thrust tectonics in the south central Pyrenees
Structural history of high-pressure metamorphic rocks in the southern Vanoise massif, French Alps, and their relation to Alpine tectonic events
Development of conjugate shear bands during bulk simple shearing
Microscopic deformation mechanisms associated with mica film formation in cleaved psammitic rocks
An examination of the cataclastic fabrics and structures of parts of Nisutlin, Anvil and Simpson allochthons, central Yukon: test of the arc-continent collision model
Graphic determination of principal stress directions for slickenside populations: an attempt to modify Arthaud's method