You can change how Google Earth Version 4 displays the terrain (physical layout) of the areas you visit. There are two relevant options:
Terrain Quality - This setting allows you to determine how coarse or fine the Earth's terrain appears in Google Earth. To access these settings, click Tools > Options > 3D viewer tab (on the Mac, click Google Earth > Preferences > 3D View tab). Under Terrain Quality, use the slider to choose the appropriate level of detail. Using a Lower (faster) settings improves performance of Google Earth, but terrain appears less detailed. Using a Higher (slower) setting improves the depiction of terrain, but at the cost of performance.
Elevation Exaggeration - In this same dialog box (see above), change the Elevation Exaggeration value to depress or exaggerate terrain as it appears in the 3D viewer.
Learn more about these and other related options.