OK you know the cycle path conecting eterna city and oreburgh city, to get a gible use cut on the trees to go under the cycle path. Then go all the way to the end until you see a cave - but don't go in the cave, go down a bit to the tree then go right so your under the cycle path.
Then go up and there is a secret cave entrance under the cycle path. Then go down the stairs and keep running round until you get a wild Gible also you will find lots of stuff, including the TM Earthqauke.