ABSTRACT Rampart craters are omnipresent features on volatile-rich solid planetary surfaces. This raises the question whether, and how many, rampart craters are present on Earth. We reviewed the terrestrial impact crater record with regard to possible rampart morphologies and present detailed morphological analyses of these terrestrial craters here. Our results show that the Ries crater in Germany, Bosumtwi crater in Ghana, Tenoumer crater in Mauritania, Lonar crater in India, and Meteor crater in the United States are terrestrial rampart craters. The Ries and Bosumtwi craters can be classified as double-layer ejecta (DLE) craters, whereas Tenoumer, Lonar, and Meteor craters can be classified as single-layer ejecta (SLE) craters. Tenoumer and Meteor craters show rampart as well as common lunar-like ejecta characteristics within their ejecta blankets and, thus, appear to be hybrid craters. In addition, we discuss seven crater structures that show at least some morphological or lithological peculiarities that could provide evidence for possible ejecta ramparts. Considering the low number of terrestrial impact craters with well-preserved ejecta blankets, the relatively high proportion of rampart craters is astonishing. Obviously, the formation of layered or rampart craters is a common and not a rare process on Earth.

Abstract The NW African continental margin is well known for the occurrence of large-scale but infrequent submarine landslides. The aim of this paper is to synthesize the current knowledge on submarine mass wasting off NW Africa with a special focus on the distribution and timing of large landslides. The described area reaches from southern Senegal to the Agadir Canyon. The largest landslides from south to north are the Dakar Slide, the Mauritania Slide, the Cap Blanc Slide, the Sahara Slide and the Agadir Slide. Volumes of individual slides reach several hundreds of cubic kilometres; run-outs are up to 900 km. In addition, giant volcanic debris avalanches are widespread on the flanks of the Canary Islands. All headwall areas are complex with clear indications of multiple failures. The most prominent similarity between all investigated landsides is the existence of widespread glide planes that follow the stratigraphy, which points to weak layers as most important preconditioning factor for the failures. Landslides with volumes larger than 100 m 3 are close to being evenly distributed over time, contradicting previous suggestions that landslides off NW Africa occur at periods of low or rising sea level. The risk associated with the landslides off NW Africa, however, is relatively low due to their long recurrence rates.

Paleozoic formations crop out extensively in Morocco, north of the West African craton. With regard to the Hercynian deformation, various structural domains can be distinguished in Morocco. The undeformed series of the southern flank of the Tindouf basin belong to the tabular cover of the Reguibate shield. Zemmour and Anti-Atlas are parts of a marginal belt, mildly deformed, around the West African craton. The Coastal Block, North-central, and Northeastern domains constitute the Moroccan Hercynian belt, which has been more or less strongly deformed between Late Devonian and Late Carboniferous times. In spite of these various states of deformation, these domains are not distinct terranes since there was a general continuity between them during Paleozoic time; they correspond to the same epicontinental shelf, itself related to the West Africa craton during early Paleozoic time. Later on, their Carboniferous sedimentary facies graded laterally from one domain to the other, and finally, no large-scale displacement occurred between them during or after their Hercynian deformation. On the other hand, three domains show sedimentological and structural differences with the rest of Morocco, which distinguish them from the areas connected with the Western Africa craton. The Western Sahara belt is a Mauritanide klippe thrusted eastward upon the craton. The Sehoul domain probably separated during Late Cambrian and Ordovician time from northern Morocco and it was accreted again to the rest of Morocco at the end of Ordovician time by a pre-Hercynian Taconic orogeny. The Internal Rif is an alpine allochthon that was located elsewhere during Paleozoic time, probably at the prolongation of northeastern Morocco. Therefore, Western Sahara, Sehoul, and Internal Rif are Paleozoic terranes.