 Before Alfred Wegner came along and proposed continental drift the prevailing wisdom of how the earth's topography was created was based on The hypothesis that the earth had contracted from its original state as a molten blob So you can kind of imagine a grape turning into a raisin and See how this raisin has some you know mountain belts and some deep valleys, which could be like the ocean floor, maybe And this model has sort of two big predictions that we can test with observations And one of them is that the crust can't move horizontally. You can only move vertically, right? The pressure caused by contraction causes some places to uplift and some places to buckle downwards But they don't move from side to side, right? And then the other prediction which is a little more subtle, but I think if you look at a handful of raisins You'll see what I mean And that is that all the elevations Are normally distributed about some mean elevation. So what I mean is that if you can picture kind of all the different elevations High and low on the surface of this raisin There should be basically a bell curve of elevations and the middle of that bell curve would be the sort of average elevation and we can actually test both of these predictions and we'll see why they don't work and Ultimately, that's one of the reasons why the contracting earth hypothesis has to be rejected