Artefacts in applications of the global gravity field and topographic models based on satellite and terrestrial data of diverse kinds are studied. Various types of artefacts are presented and analysed with the aim to understand how the artefacts originated, how to reduce them (if feasible) and to avoid misinterpretations in geoscience. We work with the gravity aspects (gravity anomalies, the Marussi tensor of the second derivatives of disturbing potential, gravity invariants and their specific ratio, strike angles, and virtual deformations), and with surface or bedrock topography. Examples for the Earth, the Moon, and Mars are presented., Jaroslav Klokočník, Jan Kostelecký, Aleš Bezděk and Gunther Kleteschka., and Obsahuje bibliografii
Moving rocks in Death Valley. When the volume of water under the ice increases the rock and ice complex becomes buoyant until it separates from the surface and can be freely transported in the water medium. As the water influx slows down and playa´s water drains, the rock and ice complex makes contact with the muddy surface and starts plowing a new narrow trail. With more water draining the rock and ice complex plows deeper and wider while thrusting a pile of mud in front, until it stops at the final location, ice melts completely leaving little sign of the carrier.