Aeolian deposits are widely distributed in the interior of the Tibetan Plateau, and their chronology is poorly known. It is not yet clear whether they accumulated only after the last deglaciation, or over a longer time. We applied quartz OSL dating to aeolian samples from the Lhasa area with OSL ages ranging from 2.9 ± 0.2 to at least 118 ± 11 ka. The probability density frequency (PDF) distribution of 24 ages reveals age clusters at about 3, 8, 16–21, 33, and 79–83 ka, indicating enhanced sediment accumulation then. The results show that aeolian deposition occurred throughout most of the last 100 ka. This implies that: 1) an ice sheet covering the whole Tibetan Plateau during the last glacial maximum (LGM) could not have existed; and 2) erosion during the last deglaciation was not as strong as previously proposed, such that not all pre-Holocene loess was removed. The age distribution shown in the PDF indicates that aeolian accumulation is episodic. Sand-formation events revealed by age clusters at 3, 8, and 16–21 ka imply roughly synchronous environmental responses to corresponding global-scale arid events.

Palaeogene trace fossils penetrate the uppermost Cretaceous sediments in the Agost section, Betic Cordillera, SE Spain. Chondrites ?targionii, Zoophycos isp., Planolites isp. A, Planolites isp. B, ?Thalassinoides isp. A, Thalassinoides isp. B, Thalassinoides isp. C, Alcyonidiopsis longobardiae, and Diplocraterion ?parallelum have been identified. A well-developed endobenthic tiering pattern is interpreted. The uppermost tier (A) represents major benthic activity in the shallowest sediments at or just below the seafloor, recorded as bioturbated background (only discrete rare Planolites). The next upper tier (B) displays the highest trace-fossil diversity, with Planolites in the shallow levels, and Thalassinoides and Alcyonidiopsis at slightly deeper ones. The intermediate tier (C) contains randomly distributed Thalassinoides and Alcyonidiopsis, cross-cut by Zoophycos and large and medium-sized Chondrites. The deepest tier (D) contains Zoophycos, cross-cut by medium- and mainly small-sized Chondrites. Two interpretations are proposed: (1) vertical partitioning of a singled multi-tiered community under steady-stable conditions in well-oxygenated water bottom, reflecting gradual changes deep into the sediment, with decreasing oxygen pore water and benthic food, and increasing substrate consistency, and (2) sequential colonization and community replacement, reflecting the work of two successive communities. The first community, mainly represented by Planolites, Alcyonidiopsis and Thalassinoides, was produced in a shallow, oxygenated soft substrate. Probably related to decreasing oxygen content and benthic food availability, this community was replaced by deeply burrowing organisms that produced Zoophycos and Chondrites. This sequential colonization can be determined by changes in environmental parameters related to the Cretaceous–Palaeogene (K–T) event, or may have resulted from normal ecological and early diagenetic processes.