The causes were: over 60 mm of rainfall (typically a month's rainfall) fell in two hours; the ground was already saturated due to the previous two weeks of above average rainfall; the drainage basin has many steep slopes, and has areas of impermeable slate causing rapid surface run-off; Boscastle is at the confluence (where tributaries meet) of three rivers - Valency, Jordan, and Paradise; The names Jordan and Paradise may have been borrowed from the Bible by a reinterpretation of the French "jardin", i.s.the garden of Bottreaux Castle; Armstrong, W. J. C. (1931) A Rambler's Guide to Boscastle; 2nd ed.