some closing remarks on Moseley and glacial motion

During the middle decades of the 19th C Henry Moseley wrote a series of papers challenging the then emerging orthodoxies as to what provides the power necessary to move glaciers down alpine valleys. Based upon his own measurements of the shear strengths of ice he fairly convincingly demonstrated that the forces provided by gravity acting alone are incapable of providing the levels of power required to overcome the material strengths and enable the observed movements of glacial ice. His arguments would have been even more powerful in the context of continental ice sheets where the forces of gravity are generally considerably less than even the mildest of alpine glacial valleys. He argued, and some of the most influential scientists of the day agreed, that the missing energy was derived from fluctuations in the levels of the solar energy being absorbed by the glacial ice. Although his early papers suggested a fairly simplistic explanation as to how these fluctuations in solar energy, become manifest in terms of mechanical energy in the form of expansions and contractions, Moseley did not get the chance to elaborate on how he thought this model would work in glacial motion. He had, it is true, identified how this action could move a solid sheet of lead or even ice down an inclined slope. But the papers promised in his last contribution on the subject of glaciers, published in September 1871, did not appear before his death in January 1872. This is to be regretted, since the ideas he was exploring and which promised to help explain the power needed to propel glacial ice have since been seemingly neglected.

I am hopeful that the short accounts in the last few postings, outlining some of the exchanges that took place in the middle decades of the 19th C, along with some more recent reconsideration of the possible influences from alternations in thermal energy, might result in reconsideration of current models for the movement of glaciers. There seem to be some important issues that remain imperfectly understood. It seems clear to me, for example, that even if the forces of gravity are considered capable of explaining glacial motion then with the even greater energies potentially derived from alternations in the solar energy entering the glacial ice it should be even easier to explain these movements. At the very least the unfinished but productive debate of the mid. 19th C could be usefully reopened. It is possible that by doing so some of the paradox within current theories of glacial action may be more convincingly resolved. Rather than trying to explain all glacial motion in terms of either gravity or thermal action, it is to be hoped that both will come to be seen as providing in differing circumstances varying but important contributions to the power necessary to move glaciers. In these circumstances it is to be hoped that the important contributions from Canon Henry Moseley might be given the credit they would appear to deserve.