Weathering of coastal defensive structures in southwest England: A 500 year stone durability trial

Historic structures can be viewed as exposure trials of the stone of which they are constructed. As such, they represent a geomorphological weathering experiment. Several structures of Henrician (sixteenth century) and greate r age on the coast of southwest England have been exposed to coastal salt w eathering for 500-600 years. Long-term weathering rates on five different r ock groups are derived from careful study of weathering depths and forms. T here is significant variation in weathering rate between five major rock gr oups. Rank ordering of weathering rate values reveals a durability order of these rock groups, which is confirmed by local juxtapositions. Controls on rock durability in the coastal weathering environment include both mechani cal and mineralogical characteristics. Specific density, and combined quart z and muscovite content, are positively related to durability; high feldspa r and chlorite content are associated with low durability. Copyright (C) 20 00 John Wiley & Sons, Ltd.