Widespread Amazonian-aged fluvial channels have been mapped proximal to Lyot crater, a ~225 km diameter impact basin in the northern lowlands of Mars. Comparable in area to some Noachian/Hesperian fluvial systems, their morphology differs, being dominated by broad, shallow braided channels. Using new developments in the study of cratering, water inventory, and climate history, we assess eight d...

[1] We present evidence that a final epoch of widespread fluvial erosion and deposition in the cratered highlands during the latest Noachian or early to mid-Hesperian was characterized by integration of flow within drainage networks as long as 4000 km and trunk valley incision of 50 to 350 m into earlier Noachian depositional basins. Locally deltaic sediments were deposited where incised valley...

In the largest known population of sinuous ridges on Mars, Aeolis Serpens stands out as the longest ( 500 km) feature in Aeolis Dorsa. The formation of this landform, whether from fluvial or glacio-fluvial processes, has been debated in the literature. Here we examine higher-resolution data and use a terrestrial analog (the Mirackina paleoriver, South Australia) to show that both the morphology...

There is significant debate over the rates and types of fluvial activity at the Plio-Pleistocene boundary in the hyperarid Atacama Desert of Chile. To quantify fluvial processes and help resolve this debate, we measure terrestrial cosmogenic nuclide (TCN) (Be and Ne) concentration depth profiles in three settings representing a chronosequence: (1) a late Pliocene alluvial fan representative of ...

Uranium-thorium dating of speleothems from two caves in the Junee-Florentine karst, Tasmania, provides some age constraints for associated clastic sediments including coarse dolerite-rich fluvial gravels, which underlie the three oldest dated speleothems. The results suggest minimum ages of 15 ± 5 ka, ~325 ka and >350 ka (two dates) for the gravels, implying that they are considerably older tha...

An isolated pterosaurian caudal cervical (~ postcervical) vertebra was recovered from the Upper Cretaceous Lapurr sandstone of West Turkana, northwestern Kenya. The vertebral centrum is short, wide, and dorsoventrally compressed. Although the specimen is lightly built similar to most pterosaurs, it is here referred to Pterodactyloidea and tentatively to the Azhdarchidae in that it lacks pneumat...

Introduction: The Hypanis fan-shaped deposit in Xanthe Terra has been interpreted by many to be a late Noachian aged delta along the dichotomy boundary [15]. The putative delta was a compelling candidate landing site for the future Mars 2020 and ExoMars rover missions as it was positioned at the edge of an open basin, could have been an ideal environment for biosignature formation, concentratio...