SEDIMENTARY ENVIRONMENTS/Contourites 513 restricted to the photic zone like their warm shallowwater counterparts such as those from the Caribbean described above However, they have an analogous complex associated fauna The extent and thickness of these cold-water carbonates in the northern and southern hemispheres has become known only in the last 20 years or so, and the full geological impact of their discovery has yet to be established Many Miocene limestones from southern Europe are now believed to be of temperate origin as are some Late Palaeozoic limestones of North America and southern Australia Because of their more limited extent, coldwater carbonates have fewer economic uses than their tropical counterparts In the coastal areas of northwestern Europe the calcareous algae are dredged for use as agricultural and horticultural fertilizer and for liming the acidic soils of the region However, because of the low growth rates of the carbonate producers, this is a non renewable resource Conclusions From this review it can be seen that continental shelf seas have extensive areas of carbonate sediment accumulation The nature and distribution of these areas are mainly controlled by climate and morphology Although pelagic sediments forming in deep ocean waters are more abundant today, their usual geological fate is to disappear into subduction zones This explains why limestones formed in shelf environments are the commonest type of limestone in the geological record If we are to understand how limestones formed and what controls their distribution and composition, we must study their modern counterparts To conclude, carbonate shorelines and shelves are important features of the world’s sedimentary and biological systems; they contain the biologically diverse and economically important habitat of tropical coral reefs, analogues for the interpretation of ancient limestones, and some of the most attractive coastlines of the world See Also Diagenesis, Overview Fossil Invertebrates: Corals and Other Cnidaria; Bivalves Microfossils: Foraminifera Minerals: Carbonates Sedimentary Environments: Reefs (‘Build-Ups’) Sedimentary Processes: Karst and Palaeokarst Sedimentary Rocks: Dolomites; Limestones Seismic Surveys Further Reading Bosence DWJ and Wilson RCL (2003) Carbonate depos itional systems In: Coe A (ed.) The Sedimentary Record of Sea level Change, pp 209 233 Milton Keynes and Cambridge: The Open University and Cambridge University Press Jones B and Desrochers A (1992) Shallow platform carbon ates In: Walker RG and James NP (eds.) Facies Models Response to Sea Level Change, pp 227 301 St Johns: Geological Association of Canada Light JL and Wilson JB (1998) Cool water carbonate de position on the West Shetland Shelf: a modern distally steepened ramp In: Wright VP and Burchette TP (eds.) Carbonate Ramps, pp 73 105 Special Publication 149 London: Geological Society Purser BH (ed.) (1973) The Persian Gulf: Holocene Car bonate Sedimentation and Diagenesis in a Shallow Epicontinental Sea Berlin: Springer Verlag Tucker ME and Wright VP (1990) Carbonate Sedimentol ogy Oxford: Blackwell Scientific Publications Wright VP and Burchette TP (1996) Shallow water car bonate sediments In: Reading HG (ed.) Sedimentary Environments: Processes, Facies and Stratigraphy, pp 325 394 Oxford: Blackwell Science Contourites M Rebesco, Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Italy ß 2005, Elsevier Ltd All Rights Reserved Introduction Contourites are sediments deposited or substantially reworked by the powerful action of bottom currents The study of contourites is important in at least three main respects: palaeoclimatology, hydrocarbon exploration, and slope stability The continuous and relatively high-resolution record included in these sediments is crucial for palaeoclimatology since it holds the key for priceless information on the variability in circulation pattern, current velocity, oceanographic history, and basin interconnectivity Bottom currents are a crucial factor in oil and gas reservoir development since weak