3.2. Pre-trenching studies

In order to confirm first investigations, it was decided to excavate some sites (so called pre-trenches). It was especialy usefull at Achenheim where an important fault observed by Wernert in 1937 was rediscovered (due to evolution of the quarry wall, vegetations). Examination of old literature, photographs and drawings of this time allowed us to precisely position the presume trace of this fault on an actual map.

FSite photography

Some pre-trenching work was also performed successfully at Saverne and Riedseltz where normal and also reverse faulting were observed.

Example of Riedseltz quarry pre-trenching study. Slickensides (N170 normal sisnistral ) were observed (upper left). Fault appears to affect Pleistocene sands up to the top of the outcrop. The total offset is greater than 4 meters. Dating pending.