SEDIMENTOLOGICAL CHANGES ACROSS THE ORDOVICIAN-SILURIAN BOUNDARY IN HADELAND AND THEIR IMPLICATIONS FOR REGIONAL PATTERNS OF DEPOSITION IN THE OSLO REGION - A REPLY

Baarli (this issue. pp. 253-255) provides general support For our mode l of an easterly supply of sediment into the Oslo Region during the la test Ordovician and Rhuddanian. Our block model for the basin is neces sarily schematic but, importantly, shows a series of half-grabens with their basement surfaces tilted eastwards. The interplay between fault movement and rate of sediment supply was thus able to produce sea flo or topographies which differed from half-graben to half-graben and cou ld show Local eastward deepening, but with the overall transport of si liciclastic material into the basin from the east. However, Baarli als o provides new and convincing evidence for the derivation of sediment of a new provenance, from the west, during the Aeronian. Our basin mod el can accommodate this with the continuation of an eastern source and westward dipping palaeoslope in the Hadeland segment of the basin.