We have used the NEXTMap Britain digital terrain model (DTM) to determine the lithospheric response to erosional unloading and the contribution of tectonics, in the form of elastic plate flexure, to the Cotswold ‘scarp and vale’ landscape. The calculations take into account lithology variations and along-strike changes in escarpment retreat. We show that flexural rock uplift as a result of erosional unloading varies spatially and may contribute up to 50% of the relief in the Cotswold region. This is supported by morphometric analysis, of concavity and steepness, for 66 longitudinal river profiles that drain the scarp and dip slope of the escarpment. Viscoelastic plate models suggest that the uplift is initially rapid (up to 8 m ka −1 ) and essentially complete within 50 ka. These initial rates are compatible with an early post-Anglian incision rate inferred from the Thames terraces. The ‘staircase’ terrace pattern suggests, however, that there have been a number of denudational isostatic events, each associated with a climate cycle. Finally, the analysis reveals an inherited ‘proto-landscape’ that has a subdued relief when compared with the modern DTM. Such a relief is consistent with an early extension of the River Thames, through the Vale of Moreton, to the north of the present-day Cotswold Hills.

Volcanoes may erupt explosively. Meteoroids may explode on entering the atmosphere. A microwaved grape may explode (Conover, 2019). However, a growing body of research suggests that biodiversity at the dawn of the Cambrian Period did not explode. Data, amassed in the century and a half since Charles Darwin (1859) agonized that the apparent absence of Precambrian lifeforms was the weakest link in his theory of evolution by natural selection, support the view that biological diversity at the beginning of the Cambrian Period did not burst violently, detonate, shatter, or blow up. In this contribution, we trace the origin of the phrase "Cambrian explosion," give reasons for moving away from using it, and offer an alternative for describing intervals of significant increase in the diversity of life. The bibliographic pedigree of the phrase "Cambrian explosion" is uncertain; its origin is not clearly established in peer-reviewed literature. By the early twentieth century, the abrupt appearance of abundant (macro-) fossils in the Cambrian was canon in historical geology textbooks (Schuchert and Dunbar, 1933). The earliest use of the adjective "explosive," with reference to an evolutionary rate, was likely George Gaylord Simpson's "explosive evolution" to describe a general pattern of rapid diversification early in the history of a lineage (Simpson, 1944). Mid-twentiethcentury contemporaries echoed use of this phrase in characterizing a general evolutionary pattern (Henbest, 1952; Colbert, 1953). Use of the phrase "explosive evolution" to describe rapid diversification during the early Cambrian morphed into "The Cambrian Explosion" under obscure circumstances. The earliest published occurrence known to us is a section heading in an early version of an experimental high school biology curriculum

No abstract