- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
With reference to a paper by W. B. Harland, R. H. Wallis, and R. A. Gayer on the lower Hekla Hoek succession in Spitsbergen (for reference, see this Bibliography Vol. 31, No. 9, 18 E67-08273), problems of Precambrian correlation are discussed. Rather than an unbroken sequence unconformably overlying Lewisian (Precambrian) basement rocks and unconformably overlain by Cambro-Ordovician beds, the Torridonian is divided into an upper and a lower unit separated by a stratigraphic break representing a time interval of at least 50 million years.