ESS104H1 Lecture 5: Lec 5 Expanding Earth v. Seafloor spreading
Document Summary
Supported the idea that the earth was getting bigger. Dirac (1937): g (gravity) decreases with time, proportional to t (age of universe). At that time t was considered to be 2x10^9 years. Estimate for t of 6. 5 x10^9 and 12x10^9. In the past 3. 25x10^9 the circumference of earth would have increased by 4. 5% or 1100 miles at avg. rate of 0. 5mm a year. This expansion should still be recorded in cracks widely distributed over the ocean floors. No compelling evidence of nature for or against dirac"s hypothesis. Egyed: long advocated an expansion of earth on geological grounds, estimate rate of increase in circumference of 3. 8mm a year. Info of earth has never been well integrated; contributed by: statigraphers, Precambrian geologists, students of physics of earth and oceanographers. Thanks to international geophysical year, progress in oceanography has been rapid. 1956: edwin and heezen: mid-ocean ridges form a continuous, seismically active belt, extending through the atlantic, indian and south pacific oceans.