Those Christians who accept the concept of the "geological ages" commonly have to explain away the great deluge by assuming it was not really a global flood. They realize that any flood that would rise until "all the high hills, that were under the whole heaven, were covered" and in which "every living substance was destroyed which was upon the face of the ground" (Genesis 7:19, 23) would undoubtedly eliminate any evidence of the supposed geological ages. Therefore, they have suggested modifying the Bible record to mean an overflow of the Euphrates River or some such phenomenon which would destroy just the peoples of the "known" world at that time.
There are numerous problems with this "local flood" notion, however. Appendix 6 of The New Defender's Study Bible, for instance, lists 100 reasons why the biblical Flood must be understood as worldwide and cataclysmic.
But probably the best argument is that such an argument makes God out to be a liar! God promised Noah that this kind of flood would never be sent on the earth again. There have been innumerable river floods, tsunamis, torrential regional rains, etc., in the more than four millennia since Noah's day. If God's promise referred only to some such flood as one of these, then He has not kept His Word!
But God does not lie, and He has kept His promise. There has never been another such Flood. "He that believeth not God hath made him a liar" (1 John 5:10). Theistic evolutionists, progressive creationists, and all others who believe the geological ages instead of God's Word should, it would seem, seriously rethink their position. HMM http://www.icr.org/articles/type/6/