In light of recent additions to the Palaeozoic palaeo-magnetlc database , particularly for the Ordovlclan era, a revised apparent polar wander (APW) path for Baltica has been constructed following a rigorous synthesis of all Late Precambrlan-Permlan data The APW path is characterized by two prominent loops Firstly, a Late Precambrlan-Cambrlan loop probably relating to a rifting event and secondly, a younger loop relating to a Mid-Silurian (Scandlan) colhsion event These features Imply major change In plate-tectonic reconfiguratlon Baltlca probably represented an individual continental unit m Early Palaeozoic times and was positioned m high southerly latitudes in an "'inverted" geographic orientation In such a reconstruction Baltlca was separated from the northern margin of Gondwana by the Tornqulst Sea and from Laurentla by the Iapetus Ocean The Tornqulst Zone is thus interpreted as a passive or dextral transform margin during the early Palaeozoic While undergoing counterclockwise rotations (up to 1 6°/Ma), Baltica drifted northward through most ol the Palaeozoic, except for a short period of southerly movement in Late Silurian-Early Devonian times after colhslon with Laurentla. Rapid movements in latitude (up to 9 cm/yr) are noted m Late Precambrlan/early Palaeozoic times and slgmficant decrease in velocities throughout Palaeozoic time probably reflect the progressive amalgamation of a larger continent by Early-Devonian (Euramerlca) and Permian (Pangea) times The Tornqulst Sea had a principal component of palaeo-east-west orientation. Hence it is difficult to be precise in the timing of when micro-continents such as Eastern Avalonla and the European Masslfs ultimately collided along the southwestern margin of Baltica These micro-continents are considered to have been peripheral to Gondwana (m high southerly latitudes) during the Early Ordovlclan. Eastern Avalonla clearly had rifted off Gondwana by Llanvlrn-Llandedo times and may have collided with Baltlca during Late Ordovlclan times, although the present available Sdunan palaeomagnetlc data from Eastern Avalonia may suggest colhslon in Late Silurian times Across the lapetus facing margin of Baltica, Laurentla was s~tuated in equatorml to southerly latitudes during most of the Lower Palaeozoic These continents collided in Mid-Silurian times, l e a first collision between southwestern Norway and Greenland/Scotland which gave rise to the early Scandlan Orogeny (425 Ma) in southwestern Norway possible followed by a later, but less dramatic, Scandlan event in northern Norway at around 410 Ma Since Baltlca was geographically reverted m early Palaeozoic times, the colhsional margin could not have been a margin that once rifted off Laurentm as assumed in a number of plate-tectonic models

S U M M A R YEarly Wenlock (c. 430 Ma) lavas from the East Mendips Inlier, Southern Briain, are characterized by either single-component magnetizations (Type 1) or a more complex system of three magnetization components (Type 2) during stepwise thermal demagnetization. The type of demagnetization behaviour is related to changes in magnetic petrology within the lava pile. The lower and intermediate unblocking temperature components of Type 2 represent magnetic overprints of Tertiary/Recent and Hercynian (mid-Carboniferous) origin respectively. The primary nature of the high unblocking temperature magnetization component, Types 1 and 2 (Dec = 095"C, Inc = -24", ag5 = 8.8"), is demonstrated by positive agglomerate tests. Conversely, an overlying Upper Old Red Sandstone sequence did not provide primary magnetizations; the magnetic signature is governed by syn-tectonic Hercynian remagnetizations.The primary Silurian data demonstrate that the East Mendips Inlier experienced considerable clockwise rotation, probably of the order of 80°, prior to partial remagnetization during Hercynian deformation and folding. The Silurian palaeopole (VGP: 13"N, 271"E, dp/dm=5/9) cannot therefore be used for apparent polar wander path construction. Nevertheless, the palaeolatitude estimate (13" f 5s) suggests that southern Britain (eastern Avalonia) was at comparable mid-Silurian latitudes to Baltica and northern Britain (10-20"s). Both the Iapetus Ocean and Tornquist Sea therefore, which separated southern Britain from Laurentia and Baltica respectively in Ordovician times, were closed by Wenlock time.As Ordovician and Silurian palaeomagnetic data from Baltica and Eastern Avalonia now record a comparable northwards translation from high southerly to near-equatorial latitudes during this time, we postulate pre-Wenlock collision of these blocks to form BALONIA (Baltica + eastern Avalonia). A new apparent polar wander path for eastern Avalonia constructed on the basis of this palaeogeographic model is presented.

New late Tremadoc—early Arenig palaeomagnetic results from SW Wales imply that S Britain (part of Eastern Avalonia) occupied a southerly latitude of c . 60°S in early Ordovician times. When combined with Scottish Ordoviaan palaneomagnetic data, which indicate a 15°S latitude, the results indicate that the British sector of the Iapetus Ocean reached n latitudinal width of c . 5000 km in Tremadoc—Arenig times, which was reduced to c . 3000 km by Llanvirn—Llandeilo (mid-Ordovician) times. The new data resolve two previous controversies in Palaeozoic palaeogeography. First, the high southerly palaeolatitude links Avdonia to Gondwana, marginal to W Africa, thus reconciling codlicting reconstructions based upon either palaeomagnetic or faunal/facies evidence alone. Second, reliable Llanvim palaeomagnetic data imply that Avlonia had rifted northwards by Arenig time, whereas Armorica remained proximal to northern Africa throughout the Ordovician. The combined data therefore establish that Avdonia and Armorica formed separate micro-continents when rifting from Gondwana.

Transformational growth amongst the various critical metals' markets would reduce supply concerns for industrial consumers and governments, whilst also providing commercial opportunities for the upstream industry. However, despite rapid market growth amongst some critical metal markets over the last decade, as a group they have lagged the market growth rates of the non-ferrous industrial and precious metals sectors. Research into the growth prospects of the critical metal markets is clearly required; however, their limited economic history and a paucity of data make this difficult. The economic history of the metals and mining industry as a whole, however, is better documented, and thus may provide insights into the potential for market growth amongst the critical metals. This paper therefore reviews the economic history of metals and mining, and in particular, that of the aluminium, nickel and uranium industries in an attempt to understand the key drivers behind transformational growth within the metals' markets. This historical review suggests that a combination of breakthroughs in discovery, supply and demand are required to catalyse transformational market growth; and thus that parties seeking to benefit from the transformational growth of the critical metals' markets must approach these markets in an integrated manner, considering each of the discovery, supply and demand issues in turn, rather than focusing on one specific constraint.