Introduction: Martian valley networks indicate that at least geologic conditions were different in the past, if not the climate. It is commonly believed that valley networks must be the result of groundwater sapping because their apparent drainage densities are lower than terrestrial runoff channels [1, 2, 3] (Figure 1a). It has also been suggested that valley networks are not uniformly distrib...

1 Geological evidence indicates that low-latitude polygonally-patterned grounds on Mars, 2 generally thought to be the product of flood volcanism, are periglacial in nature and record a 3 complex signal of changing climate. By studying the martian surface stratigraphically (in terms 4 of the geometrical relations between surface landforms and the substrate) rather than geneti5 cally (by form an...

We thank Britz et al. [1] for introducing Houy's [2] prescient interpretation of the significance of †Opisthomyzon for the evolution of modern remora anatomy , and regret not having discovered his elegant account ourselves [3]. Many prominent ichthyologists have considered the relevance of †Opisthomyzon since its discovery more than a century ago [4– 7], but none of their observations approache...

A 4000-km-' area of submarine slump and slide deposits along the west flank of Mauna Loa volcano has been mapped with GLORIA side-scan sonar images, seismic reflection profiles, and new bathymetry. The youngest deposits are two debris avalanche lobes that travelled from their breakaway area near the present shoreline as much as 100 km into the Hawaiian Deep at water depths of 4800 m. The two lo...

Introduction: The dichotomy boundary represents one of the most important geological and geophysical features of Mars. We have been assessing the nature of modification processes along the dichotomy boundary at northern mid-latitudes in the Deuteronilus-Protonilus region and have found evidence for extensive regional Amazonian glaciation in lobate debris aprons (LDA) and lineated valley fill (L...

In May 2010, following reports of neuropsychiatric adverse events, Health Canada compelled the makers of the newest smoking cessation prescription medication, varenicline, to carry a boxed warning label.1 Warnings regarding increased risk of aggression and suicidal thoughts and behaviour have been in place for bupropion, another smoking cessation prescription medication, since 2004.2 These warn...

The early opening of the South Atlantic ocean along the eastern Romanche Fracture Zone, including an initial phase of transform faulting and pull-apart basin formation, followed by the generation of a seafloor spreading center, was investigated during Ocean Drilling Program Leg 159 to the Côte d’Ivoire-Ghana continental margin. Clay minerals in the <0.5-μm fraction of tectonically disturbed sed...

Chapter 7 of Jim Valentine's classic book, Evolutionary Paleoecology of the Marine Biosphere, is titled "Community Ecology and Evolution" (Valentine 1973, 269-336). The first sixty-two pages of the chapter are about various general properties of community ecology and paleoecology, the next three and one-half pages concern the evolution of species within communities, and only the last two and on...

It is suggested metal-rich carbonaceous chondrites (CCs), CB, CH and Isheyevo, contain various proportions of chondritic components (CAIs, chondrules, metal) formed (i) by melting, evaporation, and condensation processes in an impact plume resulted from a planetary-scale collision, and (ii) by thermal processing of dust aggregates in the protoplanetary disk (PPD) [1−4]. The impact-plume product...

A structural investigation of the well-exposed northern and western parts of the Vredefort dome has established the geometry and chronology of pre-, syn-and post-impact deformation features. The strata display a crude polygonal geometry with zones of complex monoclinal or symmetric folding, and radial oblique-slip faulting separating relatively straight segments. Pseudotachylitic breccia is ubi...