Stratigraphic.

The permo-triassic formations Sherlock, Robert Lionel 1948 The Phanerozoic geology of the world edited by M. Moullade and A.E.M. Nairn 1978 The Pleistocene period Zeuner, Frederick Everard 1959 The precambrian Rankama, Kalervo 1963 The principles of historical geology Stovall, John Willis 1955 The stratigraphic history of Africa south of the Sahara Haughton, Sidney Henry 1963 The Tectonics of the Canadian Shield edited by John S. Stevenson 1962 The Tectonics of the Canadian Shield Stevenson, John S 1962 The ways of the weather Boggs, Sam 1987 Time in stratigraphy Shaw, Alan Bosworth 1964