[Petwksp] Hmmm

[John Goodge]

Dex et al.,

I'm in agreement with the others. In one semester of IgMet, it's more 
important in my mind to focus on the processes that form general 
classes of rocks, or that operate in the major plate-tectonic settings, 
rather than a catalog of all possible rock systems. I would much rather 
spend the time working through ternary basalt equilibria, that will 
help them understand the difference between tholeiites and alkaline 
basalts, than their chemistry. That said, with the Duluth complex in 
our backyard here, I hope they will retain what an anorthosite is!

Still, I can't help but wonder what your colleague would find if, for 
example, he polled his former students a couple of years out from 
geophysics to see if they could recall typical thermal conductivities, 
electrical resistivities or compressibilities of various rock types? 
Would these students be able to come up with reasonable heat flow 
values expected in different tectonic settings? Would they know the 
magnetic polarity timescale? Could they construct a reasonable gravity 
model without consulting a reference on rock densities? Hmmmmm.

Cheers,

John

---------------------------------------------------------------
John W. Goodge
Department of Geological Sciences
University of Minnesota
Duluth, MN  55812
Tel 218-726-8486
Fax 218-726-8275
Email jgoodge at d.umn.edu
Web www.d.umn.edu/~jgoodge