You got me, a definite error on my part. Oh well, make mistakes, even dumb ones, but fess up quick.
As to sources you could try the wiki on
Structure of the Earth, my original source is from memory of
Physics and Geology by Jacobs, Russell and Wilson, the textbook for general geophysics at New Mexico Tech back in 1980. Don't think the physics or structure has changed much since.
I think some confusion may occur because the mantle is referred to as viscous in the wiki article, however that is not synonymous with liquid and does not act that way according to physics.
{ABE} Actually managed to get a D in the class, Schlue had high standards and graded on a strict Bell Curve, took it too early, was in Calculus 3 at the same time, competition already took electrical physics and burned Maxwell into the ground. Lowest grade carried until a few years later when managed to flunk structural engineering at UNM (how embarrassing, missed last day to drop, please don't ask me to design a bridge). But I feel I remember more about that one than many I made an A in later.{/ABE}
Edited by anglagard, : Just too chatty, past bedtime
Read not to contradict and confute, not to believe and take for granted, not to find talk and discourse, but to weigh and consider. - Francis Bacon