S U M M A R Y Reflection seismics in compressional belts has revealed the structure of crustal shortening and thickening processes, showing complex patterns of indentation and interfingering of colliding crusts and subcrustal lithospheres. Generally in the upper crust large zones of detachments develop, often showing duplexes and 'crocodile' structures. The lower crust from zones of active collision (e.g. Alps, Pyrenees) is characterized by strongly dipping reflections. The base of the crust with the Moho must be continuously equilibrating after orogenic collapse as areas of former continental collision exhibit flat Mohos and subhorizontal reflections. The depth to the Moho increases during collision and decreases after the onset of post-orogenic extension, until finally the crustal root disappears completely together with the erosion of the mountains.Processes, active during continental collisions and orogenic collapse, create distinct structures which are imaged by reflection seismic profiling. Examples are shown and discussed.

Seismic reflection profiling across strong dip (more than 25°) suture zones between different crustal terranes or provinces reveals a distinct seismic reflectivity pattern of dipping reflections and associated diffractions. Suture zones in areas dominated by thin‐skinned tectonics do not show this pattern. Profiles from southern Germany (Deutsches Kontinentales Reflexionsseismisches Programm), Great Britain (British Institutions Reflection Profiling Syndicate) and North America (Consortium for Continental Reflection Profiling and U.S. Geological Survey) crossing major sutures are examined with respect to dipping reflections in the upper crust and accompanying diffractions in the lower crust. The strong resemblance of seismic patterns suggests a similar origin for these structures.

SUMMARY A systematic comparative study of the reflectivity of the continental crust is undertaken—made possible by the expanded data basis of deep seismic reflection profiles in Europe. The reflectivity is not at all the same but can change dramatically from one seismic line to the next. Different seismic reflectivity patterns—independent of applied techniques—are observed. Correlations between these seismic patterns and specific tectonic units can be found. While lamellae and bands of reflections in the lower crust are widespread in post‐orogenic extensional areas, ‘crocodiles’ seem to represent compressional zones that are occasionally accompanied by seismic duplex structures. The ‘fishbone’ pattern—many ‘minicrocodiles’—is characteristic for the old London‐Brabant Massif. The ‘ramp and flat’ structure displays the thin‐skinned tectonics of the North Variscan Deformation Front over a length of 2000 km. Diffraction clusters in the lower crust accompanied by a dipping reflection in the upper crust can be observed close to thick‐skinned deformation fronts. Diffractions are also present in rift areas, for example in the North Sea. Some regions show a decreasing reflectivity with depth. The reflections are concentrated in the upper crust and no Moho reflections can be observed. These areas can be correlated to areas with Precambrian crust.

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