Highlands controversy of Northwest Scotland

The Highlands controversy was a scientific controversy which started between British geologists in the middle of the nineteenth century concerning the nature of the rock strata in the Northwest Highlands of Scotland. The disagreement stemmed from the apparent ages of the strata, particularly the, now confirmed, existence of older rock above younger rock as well as duplicated and inverted strata, which could not be satisfactorily explained by contemporary geology. This rock formation and surrounding controversy were the impetus for Albert Heim's theory of Thrust faulting, which, in conjunction with anticlines and imbrication, are now commonly accepted as the primary geologic mechanisms that created the Northwest Highlands rock strata.^[1]

At the time, the debate became contentious, even acrimonious, because of some of the personalities involved and because it pitted professional geologists of the Geological Survey against academic and amateur geologists. An initial resolution was achieved by about 1886 but the great complexity and scientific importance of the discovery of the Moine Thrust Belt and the geological processes involved in its creation led to field work continuing for a further twenty years culminating in the 1907 publication by the Geological Survey of a book of fundamental geological significance: The Geological Structure of the North-West Highlands of Scotland.

The acrimony was an important factor in the political decision to set up the Wharton Committee of 1899 to review the state-funded Geological Survey. The committee's report probably precipitated the retiral of Archibald Geikie, the Survey's director-general, who had been slow to accept the new geological paradigm. However, in retirement Geikie's status flourished as he went on to become president both of the Geological Society and the Royal Society and to receive the Order of Merit.

The northwest highlands region of Scotland is now known to be where part of the Iapetus Ocean closed with the collision of the continents of Laurentia and Baltica about 400 million years ago. The consequent Caledonian Orogeny produced intense folding and compression of rocks – at thrust faults older rock strata slid for miles over younger rocks and, at nappes, the sequences of rock strata became inverted and duplicated at overturned anticlines.