So the Tibetan Plateau is a petrified tree stump? LOL. Okay.
Dirt, soil is made up of clay minerals which are called hydrous alumino phylloslicates. They are basically decomposed continental crust/bedrock which is granite. The main constituents of granite are aluminum (Al) and silica (SiO2) along with cations such as Ca and Na, K, and lesser amounts of Mg, Fe and H20. As a result of their parentage, clay minerals are not that much different than their parent, except for a large addition of water, which is to be expected if you have decomposed granite interacting with groundwater.
Examples of clay mineral chemical formulas:
Kaolinte - Al2Si205(0H)4
Illite - (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)]
Chlorite - (Fe, Mg, Al)6(Si, Al)4O10(OH)8
Vermiculite-(Mg,Fe,Al)3(Al,Si)4O10(OH)2•4(H2O)
Montmorillonite - (Na,Ca)0,3(Al,Mg)2Si4O10(OH)2•n(H2O)
Now, conversely petrified wood consists of SiO2 (chalcedony - which is another form of quartz).
So if the Tibetan Plateau is a petrified tree stump, then it must be a huge chunk of quartz?
Is the plateau completely lacking of soil/dirt?
No, it is continental crust (granite) covered by a layer of soil.
That sciency thing allows us to observe and calculate pesky things like chemical formulas, which in geology trace daughter rock to parent rock. Sort of like DNA for rocks.
The Tibetan Plateau formed via the collision of Indian into the Asian continent. It is not a friggen tree stump.