Superfaults

A year-long world-wide flood would significantly change the Earth's contours. Also, in the years immediately following the flood, there can be a lot of movement of the Earth as it regains equilibrium.

As reported in the Nov, 2008 Acts & Facts:
"The Heart Mountain detachment fault in northwestern Wyoming near Yellowstone National Park is the largest continental rockslide known on earth. this mass of rock, more than 400 square miles in area and over 1,000 feet thick, moved rapidly down a slope of less than 2 degrees at an estimated speed of 50 miles per hour."

The article discusses a possible way the immense friction of this rock formation could be reduced to allow the movement. You can read the article at http://www.icr.org/article/4154/

This is not an appeal to the "God of the gaps."
Rather, it is a phenomena more easily explained within the context of a major earth-wide catrastophe which saw the earth's tectonic plates move vast distances and had long-range effects, such as the movement of the Heart Mountain detachment fault.