In J. Marvin Herndon 's model, inner, large-core planets formed by condensation and raining-out from within giant gaseous protoplanets at high pressures and high temperatures. Earth's complete condensation included a roughly 300 M E gas/ice shell that compressed the rocky kernel to about 66 percent of Earth's present diameter. T Tauri eruptions of the Sun stripped the gases away from the inner planets. Mercury was incompletely condensed, and a portion of its gases was stripped away and transported to the region between Mars and Jupiter, where it fused with in-falling oxidized condensate from the outer reaches of the Solar System and formed the parent material for ordinary chondrite meteorites, the Main-Belt asteroids, and veneer for the inner planets, especially Mars. The differences between the inner planets are primarily the consequence of different degrees of protoplanetary compression. There are two types of responses to decompression-driven planetary volume increases: cracks, which were formed to increase surface area, and folding, which created mountain ranges to accommodate changes in curvature.