The research reported in this thesis represents a significant advance in the establishment of the very long-lived bivalve mollusc Arctica islandica as a high-resolution natural archive for the temperate and boreal shelf seas. Annual banding, synchronous growth within populations and a remarkable longevity which is known sometimes to exceed 400 years are clear indications that the increments in the shell of A. islandica have the potential to function as a marine equivalent of tree-rings in a geographic region (the shelf seas surrounding the
North Atlantic) whose proximity to the thermohaline overturning circulation makes it of key importance to the Earth's climate. Here, a 489-year crossdated chronology has been constructed using clams from Irish Sea waters off the south and west coasts of the Isle of Man. The chronology is made up of fifty-eight time series from forty-two individual animals, and the chronologically earliest specimen lived from 1515 to 1665. The use of geochemical proxies (14C and
o13C) to monitor the development through time of the marine radiocarbon reservoir age correction (ΔR) and the o13C Suess effect is demonstrated. It is
shown that the chronology standardized growth indices (SGls) are significantly but intermittently correlated with air temperatures from the Central England Temperature record and with locally measured seawater temperatures. Chronologies are constructed using three different detrending techniques designed to preserve low-frequency signals and the differences between the techniques are assessed.