Contributions to the Theory of Magmatic Cycles

Abstract

It is quite clear that Professor Joly's presentation of his theory of basaltic cycles is, taken alone, far too simple to match the complex details of geological history. In a former paper I attempted to extend the principles he has so persuasively advocated, by adding the conception of a peridotite cycle of longer period, and I was careful to point out that even this extension led to no more than a rough approximation to the actual realities of the earth's behaviour. As soon as details are considered, the pursuit of the subject leads its explorer into a maze of difficulties, because of the many interfering factors that must also be taken into account. Nevertheless, a broad survey of the earth's history suggests that Joly has surmised what is so far the only kind of process that even begins to correspond with the dominant facts. And that, without any qualification, is a very great achievement.