A modern perspective on the Conrad Discontinuity
Article first published online: 3 JUN 2011
©1989. American Geophysical Union. All Rights Reserved.
Eos, Transactions American Geophysical Union
Volume 70, Issue 29, pages 713–725, 18 July 1989
How to Cite
1989), A modern perspective on the Conrad Discontinuity, Eos Trans. AGU, 70(29), 713–725, doi:10.1029/89EO00223., and (
- Issue published online: 3 JUN 2011
- Article first published online: 3 JUN 2011
V. Conrad in 1925 postulated that seismic energy propagated in a lower crustal layer with a velocity intermediate between that of the upper crust and mantel. That suggestion led to the idea of a universal or at least pervasive midcrustal velocity discontinuity, a concept that soon became widely, albeit not universally, accepted. As early studies of earthquake records were supplanted by data from controlled-source refraction surveys, references to the “Conrad discontinuity” in the continental crust became common in theliterature.
As more and increasingly detailed data have been collected, the nature and even the existence of this feature has been called into question. However, some results of deep seismic reflection profiling seem to indicate a distinction between upper and lower crust, which suggests that a midcrustal boundary may indeed exist in some areas. In light of these developments and the continuing debate over the nature of the continental crust, it is appropriate at this time to examine the historical development of the concept of the Conrad discontinuity and the objections and responses and how recent data affect perspectives on the Conrad discontinuity.