Abstract The mine caves of Naica (Chihuahua, Mexico) are famous because they host large gypsum crystals. Mine works intersected new caves hosting the largest crystals in the world in the year 2000. From 2006 these caves became the object of a multidisciplinary research project with the goal of inferring their ages, the boundary conditions for their formation and the mechanisms inducing their development. Several other scientific aspects were also considered, including palynology, mineralogy, microbiology, physiology, hydrogeology and astrobiology. From 2006 to 2009, scientists and explorers tried to ensure the complete documentation of these natural wonders because they were expected to be accessible for only a few years. As a result of their location c. 160 m below the natural groundwater level, they were predicted to be flooded with thermal water as soon as dewatering of the mine ceased. This occurred at the end of 2015, so that the lower part of the mine is already submerged and in the near future the giant crystal caves will also disappear. Theoretically, it is still possible to maintain these incredible wonders for future generations, but this seems highly unlikely. Soon the crystals will be submerged below c. 150 m of hot water, restarting their incredible slow growth.

Abstract Course Note 41 represents a unique documentation of the wide variety of structural styles in the offshore Niger Delta region. Twenty-five seismic profiles are presented for their structural and sequential stratigraphic interpretation. Each is accompanied by instructions and discussion and keyed to a line drawing of a regional profile. These materials, together with background information and a reprint of a key article, not only provide a realistic context for geologic education but they are also highly relevant to global deepwater exploration.