A new regional compilation map and U-Pb ages on a suite of variably deformed, Ordovician, calc-alkaline intrusive igneous rocks requires a reinterpretation of the nature of continental collision and extensional exhumation of deep-seated rocks of the Western Gneiss Region west and northwest of Trondheim. A suite of calc-alkaline plutonic rocks, in the age range 482 to 438 Ma, previously known from the region of Smøla-Hitra-Ørlandet-Froan above the Høybakken extensional detachment fault associated with the Devonian 'Old Red Sandstone' basins, is shown to extend over wide areas below the fault, commonly as strongly foliated and lineated gneisses that had been previously mistaken for parts of the Proterozoic Western Gneiss Region. At Follafoss, a member of this intrusive suite is unconformably overlain by weakly metamorphosed conglomerate and volcanogenic sedimentary rocks of probable Late Ordovician age, suggesting that both the sedimentary rocks and the underlying intrusions correlate with the Støren Nappe in the upper part of the local sequence of Caledonide nappes. U-Pb evidence of metamorphic ages from deep-seated rocks of the Western Gneiss Region include: 1) zircon reaction rims on Proterozoic igneous baddeleyite in the Selnes Gabbro at 401 ؎ 2 Ma; 2) widespread development of zircon overgrowth and metamorphic zircon with omphacite and coesite inclusions from the Hareidlandet eclogite at 402 ؎ 2 Ma; and 3) extreme Devonian thermal resetting and neocrystallization of titanite over a wide area of the Proterozoic basement gneisses ending at 395 ؎ 3 Ma, here fully documented for the first time. At Kjørsvika, west of Trondheimsfjord, a ductilely deformed gneiss of the Ordovician intrusive suite contains igneous titanite dated at 455 Ma that shows little evidence for Devonian thermal resetting. This gneiss lies only 1 to 2 km northwest from a large area of Proterozoic gneisses with 100 percent Devonian reset titanite across a ductilely deformed contact that must represent a phase of extensional detachment (Agdenes detachment) much older than the more brittle detachments (compare Høybakken detachment) associated with some of the present outcrops of the Devonian clastic basins. These and other relationships suggest the following broad sequence of Siluro-Devonian events in the region: A) Early Scandian (430 -410 Ma) thrusting with emplacement of the composite Støren Nappe onto the relatively cool Baltoscandian margin of Baltica during contemporaneous subduction of its distal part, locally

The Caledonide Orogen in the Nordic countries is exposed in Norway, western Sweden, westernmost Finland, on Svalbard and in northeast Greenland. In the mountains of western Scandinavia, the structure is dominated by E-vergent thrusts with allochthons derived from the Baltoscandian platform and margin, from outboard oceanic (Iapetus) terranes and with the highest thrust sheets having Laurentian affinities. The other side of this bivergent orogen is well exposed in northeastern Greenland, where W-vergent thrust sheets emplace Laurentian continental margin assemblages onto the platform. Svalbard's Caledonides are disrupted by late Caledonian faults, but have close affinity with the Laurentian margin in Northeast Greenland. Only Svalbard's Southwestern terrane is foreign to this margin, showing affinity to the Pearya terrane of northern Ellesmere Island in arctic Canada. Between the margins of western Scandinavia and eastern Greenland, the wide continental shelves, now covered by late Paleozoic and younger successions, are inferred to be underlain by the Caledonide hinterland, probably incorporating substantial Grenville-age basement. In northernmost Norway, the NE-trending Caledonian thrust front truncates the NW-trending Neoproterozoic Timanide orogen of northwest Russia. Much of the central and eastern parts of the Barents Shelf are thought to be underlain by Caledonian-deformed Timanide basement. Caledonian orogeny in Norden resulted from the closure of the Iapetus Ocean and Scandian collision of continent Baltica with Laurentia. Partial subduction of the Baltoscandian margin beneath Laurentia in the midlate Silurian was followed by rapid exhumation of the highly metamorphosed hinterland in the early Devonian, and deposition of Old Red Sandstones in intramontane basins. Late Scandian collapse of the orogen occurred on major extensional detachments, with deformation persisting into the late Devonian.

Agriculture is inherently multifunctional. It jointly produces more than food, fibre or oil, having a profound impact on many elements of economies and ecosystems. A comprehensive framework is used to present new data on annual external costs in Germany ( 1.2 billion; US$2 billion), in the UK ( 2.3 billion; US$3.8 billion) and in the USA ( 21 billion; US$34.7 billion). These costs are equivalent to 49-208/ha (US$81-343/ha) of arable and grassland. Agriculture also produces positive externalities, and though there is no comprehensive valuation framework, the public benefits in the UK appear to be in the range of 10-30 (US$16-49) per household, or some 20-60/ha (US$32-100/ha) of arable and pasture land. These external costs and benefits raise important policy questions. In particular, should farmers receive public support for the multiple public benefits they produce? Should those that pollute have to pay for restoring the environment and human health? Policy options available for encouraging behavioural changes are of three types: advisory and institutional measures; regulatory and legal measures; and economic instruments. Three of the most promising options for discouraging negative externalities and encouraging positive ones are: (1) environmental taxes; (2) subsidy and incentive reform; and (3) institutional and participatory mechanisms. The greatest challenge, however, will be to find ways to integrate such policy tools into effective packages that will increase the supply of desired environmental and social goods whilst ensuring farmers' livelihoods remain sustainable.

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