Continental drift Permian era but failing to account for glaciation in India, Australia and South Africa. Geophysicist Jack Oliver is credited with providing seismologic evidence supporting plate tectonics which encompassed and superseded continental drift with the article "Seismology and the New Global Tectonics", published in 1968, using data collected from seismologic stations, including those he set up in the South Pacific. It is now known that there are two kinds of crust: continental crust and oceanic crust. Continental crust is inherently lighter and its composition is different from oceanic crust, but both kinds reside above a much deeper "plastic" mantle. Oceanic crust
The Defence of Duffer's Drift was written by Albert J. Marckwardt and Michael Burgoyne. The book follows a young lieutenant through successive lessons while conducting stability and counterinsurgency operations in Iraq. The winter 2005 edition of the "Canadian Army Journal" contained the following praise: Paul Hoffman, in his sequel to The Left Hand of God, The Last Four Things, used the example of Duffer's Drift by name as an exercise for Thomas Cale to solve for a defensive position for The Redeemers against the more mobile Commandos of the Folk. The problem set for Cale is to discover how to defend such a position with