PZ Myers over at Pharyngula is having his readers list which books should be considered essential (i.e. a must have) and popular reads that all bookstores should stock their shelves with. The goal is to have a list in hand that can be presented to bookstores to help them develop a decent science section. The science section would include books that the public would enjoy, and/or books that contain the fundamentals of various scientific fields. So scientists do the "leg-work" on helping bookstores have a science section worth reading.
I was perusing the comments section (to make sure I didn't copy someone else with my suggestions, fortunately several people beat me to some of them) . So far the geo-list includes (there might be others, but they weren't tagged geology):
Annals of the former world by McPhee
The Map that Changed the World by Winchester
Volcano Cowboys by Thompson
La Catastrophe by Scarth
Prarie by Savage
The Eternal Frontier by Flannery
The Man Who Found Time by Repcheck
The Seashell on the Mountaintop by Cutler
Snowball Earth by Walker
Principles of Geology by Lyell
The Dinosaur Heresies by Bakker
Wonderful Life by Gould
Your Inner Fish by Shubin
Gorgon by Ward
On Methesuleh's Trail by Ward
General Science (includes geosciences though):
A Short History of Nearly Everything by Bryson
Demon Haunted World by Sagan
If you want to add to the list (or expound upon what is here), why not make a quick post about which geo-book you think should be on the list and why (maybe a quick one on PZ's message board, or one for your own blog).
I figured Principles of Geology (the abridged version would be fine) should be an essential item on the list. It reads very well, and is a contempory of (hell it was partially the inspiration for) Origin of Species. Plus, you find some tantalizing hints at "modern" concepts springing up here and there (well, before they became mainstream). True you also deal with some archaic terminology, but it is still a good read that became the basis of modern geology.