Class 26: Discussion notes

Paleomagnetism and related topics

The table below is an an effort to pull together some of the varied information related to paleomagnetism and related topics (absolute age dating, oceanic features). Some of this is relevant to the on-going exercise; some is just for fun!

Year Land-based Paleomagnetics Marine Paleomagetics Radiometric Age Dating Ocean Basins Gravity
1040 Chines measure magnetic field
15-16th c Declination and inclination of mag field recognized
1710 Halley: secular variation
late 18th c Coulumb: instrument to measure mag field
early 19th c Gauss: mathematics of mag field
1838 Mag field measured in Paris and London
1895 Curie: remnant mag in coole rocks
1906 Brunhes: experiments with bricks demonstrate remnant mag
1910-15 Isostatic equilibr of continents
1911 Holmes’ first time scale
1926 Mercanton: Currie Pt. Land Bridges (also later)
1929 Matuyama: mag reversals
1930s Du Toit: geology of Gondwana continents Hess: negative gravity anomaly over trenches
1939-1947 Elsesser: Dynamo model of magn field
1947 Blackett: suggests magn field related to rotation
1947-1951 Blackett: develops improved magnetometer to measure weak fields
1947-1960 Holmes refined time scales
1950 Uyeda: reversed magn signal preserved
1950s Sea floor topography mapped
1953 Lamont grp: recognized marine anomalies in the Atlantic
1954 Clegg, Almond, Stubbs: first polar wandering curve; Creer, Irving, Runcorn: curve for older rocks Rothe: earthquake epicenters in oceans
1955 Menard: recognizes Mendocino and Murray fracture zones off California based on topography
1956 Runcorn: compares polar wandering curves for North Amer and Europe Lamont grp: ocean crust ~6km thick
1957 Lamont grp: recognized positive marine anomalies along Atlantic MOR; Girdler: postiive magnetic anomaly in Red Sea Girdler: negative gravity anomaly in Red Sea
1958 Mason and Raff: first map of magn anomalies in northeast Pacific Menard notes association of earthquakes with some margins; Bullard: heat flow at MOR is 5-6x rest of ocean
1959 Vacquier: fracture zones offset magn anomalies in Pacific
1959-62 Hess: “geopoetry”
1960 Reynolds: High-resolution mass spec K/Ar dates
1961 Dietz: suggests sea-floor spreading
1963 Cox, Doell, Dalrymple: first paleomagetic time scale
1963-68 Rapid development of paleomagnetic time scale