Visit any anti-creationist website and you're certain to find a discussion of varves, tiny laminae thought to be annual deposits within sedimentary strata. In some areas millions of these are found in succession, which are offered as "proof" of long ages. More importantly, many feel that this proves the Bible's account of recent creation to be in error.

In your kitchen you start a three-minute egg timer and a 60-minute hourglass simultaneously and then leave. You return a short while later to find the hourglass fully discharged but not the egg timer! Something must be wrong with at least one of the two timers.

Without a doubt, Earth is round, or nearly so. Using careful measurements from the ground and observations from space we can be certain it is essentially a sphere, with only minor bulging near the equator.