The series is broken into two branches, the continuous and the discontinuous. The branch on the right is the continuous. The minerals at the top of the illustration (given aside) are first to crystallize and so the temperature gradient can be read to be from high to low with the high temperature minerals being on the top and the low temperature ones on the bottom. Since the surface of the Earth is a low temperature environment compared to the zones of rock formation, the chart also easily shows the stability of minerals with the ones at bottom being most stable and the ones at top being quickest to weather. This is because minerals are most stable in the conditions closest to those under which they had formed. Put simply, the high temperature minerals, the first ones to crystallize in a mass of magma, are most unstable at the Earth's surface and quickest to weather because the surface is most different from the conditions under which they were created while the low temperature minerals are much more stable because the conditions at the surface are much more similar to the conditions under which they formed.