Mean annual surface displacement of the Laurichard rock glacier, French Alps

The Laurichard active rock glacier is the permafrost-related landform with the longest record of monitoring in France, including an annual geodetic survey, repeated geoelectrical campaigns from 1979 onwards and continuous recording of ground temperature since 2003. These data were used to examine changes in creep rates and internal structure from 1986 to 2006. The control that climatic variables exert on rock glacier kinematics was investigated over three time scales. Between the 1980s and the early 2000s, the main observed changes were a general increase in surface velocity and a decrease in internal resistivity. At a multi-year scale, the high correlation between surface movement and snow thickness in the preceding December appears to confirm the importance of snow cover conditions in early winter through their influence on the ground thermal regime. A comparison of surface velocities, regional climatic datasets and ground sub-surface temperatures over six years suggests a strong relation between rock glacier deformation and ground temperature, as well as a role for liquid water due to melt of thick snow cover. Finally, unusual surface lowering that accompanied peak velocities in 2004 may be due to a general thaw of the top of the permafrost, probably caused both by two successive snowy winters and by high energy inputs during the warm summer of 2003.

Neogene planktonic foraminifers from Wombat and Exmouth Plateau

Diverse, warm-water planktonic foraminiferal faunas prevailed on the Wombat and Exmouth plateaus during the Neogene, in spite of the northward drift of Australia across 10° to 15° latitude since the early Miocene. Invasions of cool-water species occurred during periods of global cooling in the late middle Miocene, late Miocene, and Pleistocene, and reflect periods of increased northward transport of cool surface water, probably via the West Australian Current. The sedimentary record of the Neogene on Wombat and Exmouth Plateau is interrupted by two hiatuses (lower Miocene, Zone N5, and upper middle to upper Miocene, Zones N15-N17), and one redeposited section of upper Miocene to uppermost Pliocene sediments. Mechanical erosion or nondeposition by increased deep-water flow or tilting and uplift of Wombat and Exmouth plateaus, resulting in sediment shedding, are the most likely explanations for these Miocene hiatuses, but which of these processes were actually operative on the Wombat and Exmouth plateaus is uncertain. The redeposited section of upper Miocene to uppermost Pliocene sediments in Hole 761B, however, certainly reflects a latest Pliocene period of uplift and tilting of the Wombat Plateau. An important finding was the occurrence of Zone N15-correlative sediments in Hole 762B without any representative of Neogloboquadrina. Similar findings in Java and Jamaica indicate that the earliest spreading of Neogloboquadrina acostaensis in the tropical region resulted from migration. The evolution of this species, therefore, must have taken place in higher latitudes. I suggest that Neogloboquadrina acostaensis evolved from Neogloboquadrina atlantica in the North Atlantic within Zone NN9, but how and where in the region this speciation took place is still uncertain