Revisiting Weertman's tombstone bed

Johannes Weertman published his first glaciological paper in 1957 only 5 years after getting his DSc in metallurgy from the Carnegie Institute of Technology. The paper presented the very first sliding law developed quantitatively from first principles, and involved the unconventional idealization of bed roughness using cubic ‘tombstones’ of rock. Since 1957, there has been a great deal of progress in understanding glacier sliding, but few studies, if any, have preserved the original tombstone geometry that was a hallmark of this first theory. The current study presents a partial reanalysis of the sliding process over a bed with tombstone obstacles using modern numerical methods. The result confirms the enduring applicability of Weertman's model as a pedagogical tool and motivates new questions about (1) folding flow near bedrock obstacles that invert normal ice stratigraphy, (2) the presence and role of stress singularities on sharp edges of bedrock, and (3) the validity of a presumption that regelation flow can be plug-like.

Maya Timeline in Uaxactun: Calendric Notations on the Mural Paintings at Structure B-XIII

Famous Uaxactun Mural paintings, which were found in Structure B-XIII, have been wellknown to Maya scholars for decades. They are considered as proof of Maya-Teotihuacan connection, and the importance of Uaxactun. On the other hand, the different scenes with musicians, nobles and warriors are beautiful source of Maya iconography. Below these paintings, also a short inscription in form of calendric notation was found. This inscription was not analyzed due to imperfect drawing, which was made by Antonio Tejeda in 1930’s. Fortunately, it was possible to create a new rendering of this inscription, thanks to preserved photographs of Carnegie Institute.