World Building: Random Goodness

Recently, I've been trying to use Scot "Kellri" Hoover's fourth installment in his "Classic Dungeon Designer Notebook" series, Old School Encounters Reference, which you can download from Kellri's Blog. In all the years I've played D&D, I never once played (or thought of playing) any of the D-Series. My group relished in the danger of being low level and would often retire characters before that were ever powerful enough to tread into the depths of the earth; however, there is a section of CDD #4 dedicated to random tables for exploring the deep earth akin to what we might have done while using the D-Series. These tables have inspired me. I decided to build a world starting with a map of the deep earth generated using these tables (and a few of own). Here is the initial result:

• Red lines are primary caverns.
• Brown lines are secondary caverns.
• Green lines are tertiary caverns.
• Blue lines are underground rivers.
• Blue Hexes are water.
• Tan hexes are encounter areas:

A16 Cavern (Sea Dragon)
C08 Special
C14 Cavern
D32 Shaft down (Frog Demon)
D07 Quarry (Fishmen)
E31 Chasm (Red Dragon)
E08 Grotto (Deep Gnomes)
E18 Lair (Sahaugin)
F09 Lair (Eye, Tentacled)
G08 Grotto (Frogmen)
H03 Shaft Down
H04 Excavation
H14 Large Shaft (Mongrelmen)
I29 Stairs
I32 Grotto (Spiders)
I03 Large Shaft
I04 Quarry (Grimlocks)
I05 Pool/Well
I06 Special
I13 Large Shaft (Giant Scorpions)
J04 Special
K02 Lair (Fishmen)
K05 Cavern (Giant Hornets)
K07 Shaft down
L02 Chasm (Giant Lizards)
L04 Cavern
L09 Cavern
L11 Stairs
L15 Pool
M27 Special
M31 Stairs (Kobolds)
M32 Cavern (Grell)
M02 Trap/Hazard
M07 Stairs
M11 Stairs (Goblins)
M14 Special
N02 Excavation (Myrmixians)
N07 Trap/Hazard
O29 Large Shaft
O03 Cavern (Grimlocks)
O12 Stairs (Wight)
P03 Cavern
P09 Special
Q26 Pit
Q30 Quarry (Bugbears)
Q31 Lair (Fungoids)
Q10 Lair (Lammasu)
R27 Quarry
R32 Cavern
R02 Pool/Well
S27 Pool/Well
S32 Chasm
T07 Grotto (Medusa)
U29 Cavern (Giant Spiders)
U31 Excavation (Fishmen)
V02 Pool/Well (Spectre)
X24 Excavation (Duergar)
X25 Lair (Hydra)
X26 Quarry (Duergar)
X32 Stairs
X08 Large Shaft
X09 Grotto (Fey)
Y28 Pool/Well
Y31 Excavation (Lich)
Z03 Shaft down

Everything here should be self-explanatory. The monsters in parenthesis have set up permanent camp in the areas they are listed with. I am inclined to understand "Special" to indicate areas either infected with pure chaos, have pocket plane access and/or are crash sites for alien starships from an ancient battle.

From here I'll work up.