No clear-cut distinction can be drawn between professionalsand amateurs in science: exceptions can not be found to any rule. 1Nevertheless, the word "amateur" does carry connotation that the 2person concerned is not fully integrated into the scientific communityand, in particular, may not fully share their values. The growth of 3specialization in the nineteenth century, with its consequent requirement of a longer, more complex training, implied greaterproblems for professional participation in science. The trend was 4naturally most obvious in those areas of science based especially on a mathematical or laboratory training, and can be illustrated in terms of the development of geology in the United Kingdom. A comparison of British geological publications over the lastcentury and a half reveals not simply an increasing emphasis of the 5primacy of research, but also a changing definition of that 6constitutes an acceptable research paper. Thus, in the nineteenth century, local geological studies represented worthwhile research intheir own right; and, in the twentieth century, local studies have 7increasingly become acceptable to professionals only if theyincorporate, and reflect into the wider geological picture. Amateurs, 8on the other hand, have continued to pursue local studies in the old way. The overall result has been to make entrance to professional geological journals harder for amateurs, a result that has been reinforced by the widespread introduction of refereeing, first by national journals in the nineteenth century and then by several localgeological journals in the twentieth century. As is a logical 9consequence of this development, separate journals have nowappeared aiming mainly at either professional or amateur readership. 10A rather similar process of differentiation has led to professional geologists coming together nationally within one or two specific societies, whereas the amateurs have tended either to remain in local societies or to come together nationally in a different way.