The area is somewhat funnel-shaped, dipping north-northwest, overlain by two roughly north-northwest - south-southeast directed parallel escarpments, forming three north-northwest - south-southeast directed mountain ridges, separated by equal directed valleys of Vallon du Lauzanier and Vallon du l'Enchastraye (Appendix 1: Geological Map). The morphology of the mountain ridges is controlled by the Grès d'Annot sandstone dips. The significant sharp cuts of the ridges (Appendix 3, Panoramic Pictures: 3.1, 3.2, 3.3 and particularly in 3.4) obviously reflects single composite units of the succession, especially seen in the upper part of the succession. Altitudes are ranging from 1985 - 2955m, resulting an average north-northwest dipping slope gradient of 12.6°.

The body of Grès d'Annot Formation is, from a structural point of view, nearly monotonous across all outcrops. Strike and dip is varying with almost negligently divergences (Appendix 1: Geological Map). Vertically, no deviation is registered at any site. Laterally, the dips differ slightly. In the northern part of the area, the body dips north-northeast, with a mean of 30° (Clar value of 354/30). If continuing along the peripheral sited mountain ridges of the area, slight dipping variances of 2 - 3° are measured and strike is differing up to 5° in both directions. Only one exception is found in the northeastern part of the area, which measures a strike deviation of 10° of the mean (Clar value of 344/30) The eastern ridge is, however, dipping somewhat less than the western. The centered Lauzanier ridge, when focusing southwards, is continuously increasing its dips, ending at the top of Tete de l'Enchastraye with a maximum dip of 39° (Appendix 1: Geological Map). Like in the other two ridges, strike deviation is neglected caused by very low differing that probably is lower than the measuring precision. The average strike and dip of the eastern mountain ridge is 354/28 (Clar value); the center ridge, 357/33; western ridge, 359/30.

The structural homogeneity of the Grès d'Annot Formation is confirmed by a nearly constant joint system. In addition to an orthogonal joint system, another intersecting set of joints is present throughout the area (Figure 7.1a). The conjugate joints are constantly perpendicular, trending almost north - south and east - west with an smooth diverting of some degrees to north-northwest - south-southeast and east-northeast - west-southwest. The intersecting set of joint is northwest - southeast directed. Noticeable is a minor differing between the strike and dip direction compared to the orthogonal joint system, which is trailing around 10 - 15°. Whether the joints are produced contemporaneously or not could not be determined for certain. Though, since joints do not feature typical characteristics that indicate diverse origin of timing, they are interpreted as developed during an equal period of tectonic activity. The north - south directed joint linear is rarely associated with feather jointing forms, which are staggered and aligned as en echelon. Apparently, these joints were produced during the maximum of the acting stress- or even strain regime. Since these staggered arranged shear resultants never were observed in the other two set of joints, the north - south trending joint linear is interpreted as the master joint. The feather joints reveals the s1 and s3 force components, which were interacting on the Lauzanier sandstone body (Figure 7.1a) Their rotation process has advanced from the original north - south- to nearly east - west trending. Perpendicular to the opening of the feathers is manifested by the extensional s3 component, while the compressional s1 component is lateral perpendicular (Figure 7.1a). The s2 component is related vertically perpendicular to the s1 component.

The observed non syn-sedimentary faults in the area are also more or less lining in a north - south direction (Appendix 1: Geological Map), same direction as the master joints and direction of dips. Only excluded by some small-scale faults, seen in the most eastern mountain ridge (Appendix 3.4: Panoramic Picture), which are trending east - west. These tectonic derived faults can be recognised because of their laterally offset, which measures a few- and occasionally 10s of metres. Since such small-scale offsets only appear laterally, the strike slip component is probably of minor importance. If the vertical offset is more significant remains unsolved, because of their lack of exposures in the outcrops. However, it seems most likely that they are greater than the lateral offset, since the boundary between the substrata and the Grès d'Annot Formation in the Vallon du Lauzanier is located at somewhat lower level as in the neighbouring flanks (Appendix 3.1: Panoramic Picture). Apparently, the block in the Vallon du Lauzanier has been downthrown (Appendix 1: Geological Map). Furthermore, this block is probably internally faulted and dividing the block into additional elongated blocks, whereby the faults are parallel to the major faulting. The structure sited in this valley resembles a graben structure, with at least two-, or more faults bounded at it long sides. This might even implicate a step fault system. In the most western part of the mapping area, another fault appears with vertically and also lateral offset (Appendix 1: Geological Map), which is visible through the abrupt breaks between the different formations. The other faults in the Lauzanier area are difficult to observe, and are of a small scale. In the most eastern part of the area, small scale and brittle break, faults are parting a block into a mosaic of more blocks (Appendix 3.4: Panoramic Picture). If comparing them with the neighbouring blocks, these blocks are either downthrown or uptrown, both cases may either be synthetic or antithetic. When these blocks are considered as an individual 300m long complex body, then this body is downthrown compared to its surrounding blocks.

In the most northern parts of the Lauzanier area, the top of the autochthonuos Grès d'Annot succession is, angular unconformably, overlain by the allochthonuos Flysch à Helminthoïdes For-mation (Picture 7.1b). This formation is part of the Schistes à Blocs, which is the most peripheral remnant of the Brianconnaise Nappes. This nappe belongs to the most outer western part of the alpine nappe thrusting system (Figure 3.2: Locality map). The Schistes à Blocs are classified as olistho-stromes, which have been layered in front of a tectonised sedi-mentary mèlange that moved towards the Grès d'Annot basin (Apps et al., 1987). The layering environment is comprised by typical chaotically structures of olisthostromes and an enormous range of sediment sizes, which varies from clays to 10s of metres big blocks. The appearance of the overthrusted contact of the Grès d'Annot Formation is continuously throughout the northern boundary of the Lauzanier area and proceeds westwards and eastwards, covering significant parts of the northern region. If considering the 30° dip of the Grès d'Annot body, the unconformity is of a low angle that is ranging from about 15 - 20°. When studying the boundary more closely, it is obvious that the nappe of Schistes à Blocs overthrusted the Grès d'Annot Formation, while the sandstones were already more or less consolidated. This is based on the lack of syn-sedimentary features in the lower, Grès d'Annot, boundary zone, which only comprise brittle breaking sediment beds and examples of distorted and dragged sandstone bodies (Picture 7.1c). Typical for theses bodies are their, northwards trending rounded ends. Those probably formed. while the nappe was overthrusted southwards and detached, dragged and rounded the edges of the sandstone bodies. Their other southwards arranged end, is in contrast, sharp edged (Picture 7.1c). In the upper boundary zone, of the nappe, which is produced by semi-brittle breaking olisthostromes and their sigmoidal forming structures random relatively large bodies, either of Grès d'Annot sandstone- or olistholithe bodies (Picture 7.1c).

Another evidence, which confirms that the Grès d'Annot Formation must have been more consolidated than the olisthostromes during the overthrusting period, is the intermediary composite sandstone units sited in the olisthostromes (Picture 7.1b). Such intermediary preserved units might be several 100s of metres long. Apparently, these composite sandstone units were sufficiently consolidated and heavy, being able to withstand the encountering forces of the overthrusting Alpine nappe. In contradiction, there are no signs of remnant preservations of either thin-bedded sandstone- or heterolithic beds in the olisthostromes. Evidently, these beds were not strong enough to resist the forces connected to the over-thrusting and therefore probably were eroded and transported off the study area. However, smaller remnants of sandstone bodies are also observed in various levels of the olisthostromes, which are sited several kilometres from the contact between the nappe and its substrate. This feature might be a parallel to the intermediary composite sandstone units. However, the individual bodies are resultants of much deeper penetrated units into the olisthostromes. Thus, obtained higher amounts of stress that progressed into strain and the breaking of the composite units, whereas the compressional forces derived from a southwards overthrusting nappe.

As the first Grès d'Annot sediments were encountering the basin, the paleo-surface of the Marnes Bleues was irregular. Thus, a common sight in the outcrop remnants of the basin is the onlap between the boundary of the two formations (Picture 6.7b). This irregularity of the paleo-basin floor was, after Apps (1987), caused by tilting of Early-Eocene Alpine loading, either sub-crustal blading or distant crustal stacking (details, Chapter 4.2). During the deposition of the Grès d'Annot Formation, the basin experienced a period of tectonic quiescence. The syn-sedimentary structures exposed in the lower super-cycle of the formation, probably only are resultants of gravity and slope balance features.

After the cessation of the Grès d'Annot deposition, another significant tectonic event was initiated as the Alpine loading reiterated its movement. While the Alps were compressing and moving, they produced nappes that were thrusted and therefore closing to the Grès d'Annot basin. The most outer part of the Alpine thrust system, the Brianconnaise Nappes, even overthrusted the Grès d'Annot basin in the northern region. Today, this event is observed as an angular unconformity between the boundary of the allochthonous Brianconnaise Nappe and the autochthonous Grès d'Annot Formation (Picture 7.1b and 7.1c). Apparently, the Grès d'Annot Formation was already consolidated enough to enable composite sandstone units to penetrate into the less consolidated allochthonous olisthostromes. Yet, the olisthostromes have eroded significant proportions of the upper part of the Lauzanier succession, since only 625m thick (Appendix 2: Log Correlation). Other northern successions exposures thicknesses of more than 1000m (Hilton et al., 1995), when their top is not eroded. Obviously, the olisthostromes caused very variable erosion amounts when thrusting into the northern part of the basin, whereas the Lauzanier area apparently was severely effected. This is evidently revealed, since the lower part of the Lauzanier succession is displaying similar composite logs when comparing other, more complete, composite logs. Logic is probably, if moving further on eastwards, into Italian Grès d'Annot exposes, an even stronger erosion has been acting that is caused by stronger influenced Alpine thrusting activity. However, this hypothesis is not studied more intensive.

When excluding the angular unconformity at the top of the Grès d'Annot succession, there are no internally structural features sited across the whole Lauzanier area that are resultants of compressional tectonic activity. Except the master set of joints that emphasises feather joint characteristics (Figure 7.1a), which indicate the former stress- or even strain regime of the body. Hereby the feather joints show that the northwest - southeast directed s1 is the highest compressional component of force. The s1 compressional force produced shear forces and probably caused the forming of the north - south trending master set of joint. Further, these shear-forces were able to rotate the feather joints from north - south- to a nearly east - west trend. Related perpendicular to the s1 is the s3 component, which reveals the northeast - southwest trending extensional force. Most likely, this joint system was produced during the Miocene and post-Miocene folding process of the Alps, since the direction of major compressional component of force is equally directed as s1 of the Lauzanier joint system.

The faulting characteristics in the Lauzanier area, comprising downtrown blocks (Appendix 3: especially in Panoramic Picture: 3.4) and maybe a graben-like structure that even suggest a step fault system, implies resultants of extensional tectonic activity. Likely is to assign a cessation of compressional tension, providing an increasing space of the body, to advance an collapse. Thus, if representing this theory, the collapsing of the Lauzanier body is post-orogenic and therefore of post-Miocene age.