BY PETER J. SMITH Department of Earth Sciences Open University Milton Keynes, U.K.

" A recent redetermination of solar composition showed that the Sun’s Fe abundance is 40% higher than previously thought and that Fe/Si and Ca/A1 atomic ratios are 30% to 40% higher than chrondritic values. These new data require a fundamental re-evaluation of the composition of the Earth’s mantle, which is likely to be chemically layered. The lower mantle, in particular, must be much richer in FeO than hitherto supposed.

D.L. Anderson, “Composition of the Earth,” Science, 243, 367-70, 20 January 1989.

" The complex border zone (1000 x 150 kin) in Turkey within which the Turkish, Arabian, Iranian, and Eurasian lithospheric plates interact, is surprisingly quiescent, only three earthquakes of magnitude 6.6 or greater having occurred there this century. However, a search of historical records back to 1500 A.D. shows that seismic activity was...

Interested in reading more?

Become a Member of

Receive full access to digital editions of The Scientist, as well as TS Digest, feature stories, more than 35 years of archives, and much more!
Already a member?