There would be a lot of geology (and some Paleontology) that we wouldn't understand. Actually, given modern GPS technology, it's hard to see how we could possibly miss discovering plate tectonics... it could have been delayed a few decades, but the chances of it being still undiscovered as of 2011 are essentially nil.
It's important to note that, just because nobody knew anything about plate tectonics prior to Wegener, that doesn't mean it wasn't happening.
1915
plate tectonics
the plate tectonics will be flat and no more volcanoes.
nobody cares but I cares
alfred wagner
Tidal waves, Earthquakes, landslides
The theory of plate tectonics helps explain the location of earthquakes, as they frequently happen along fault lines.
global tectonics in which the lithosphere divided into a number of crustal plates
In the late 1800's ... but nobody believed it for 100 years.
Nobody Knows . Reaad A book why dont you . It will answer your question
it wasnt accepted. Wegener's theory of continetal drift wasnt accepted. the theory of plate tectonics was created when scientists discovered about sea floor spreading and magnetic reversals. but i dont know when the theory of plate tectonics was created. so you can ask about that.
Plate tectonics