And the last thing – Glow. For the glow create MultiplyDivide and connect “incandescence stucco” to input1 of that MultiplyDivide. Input2 should be 0.2 less, basicly that number controls the strength of the glow. Create Luminance node, and connect MultiplyDivide to it, and connect that Luminance to material GlowIntensity.

So In the end you get shading network that look like this.

Simple eh?

* As you can see there is only one placement fot all three stucco nodes. I did that because In that way you could change the size of lava without having to grab three placement nodes. Also I left SolidFractal and granite Placements separated because they are not the same sizes and of course if you want you can animate SolidFractal movement so you can get the effect of hot lava moving beneath the cold lava.

Then set your displacement values. I used Mental Ray so I made displacement approximation node, to get nice displacement. You should get render like this:

Enjoy!