They’re not super thin like some of the more “technical” socks out there. Thicker than standard cotton summer cycling socks, but they’re not thick IMO. They feel more dense to me than something like a Smartwool.
I use both the Elite and the Elite Thermal. I can’t really tell much of a difference, both are wool.
http://www.amazon.com/Pearl-Izumi-Mens-Elite-Thermal/dp/B00943EGV8/ref=pd_sim_a_2