8. Explain more fully the two extreme degrees of metamorphism.

Two extreme degrees of Metamorphism:

The lower limit temperature of metamorphism is 100-200 degree Celsius. It does not include the physical or chemical formation of sedimentary rocks. The extreme higher limit temperature is 700-900 degree Celsius depending on the pressure and composition of rocks. The ultrahigh metamorphic temperature is 900-1100 degree Celcius. The pressure of the metamorphic process is 100-300 mega pascals.

Progressive Metamorphism is the process which leads the organism to progress towards the evolutionary process where the later stages have more evolutionary progress than the previous stages. Whereas the retrograde Metamorphism is just the reverse of the progressive Metamorphism, where the later stages have less evolutionary progress than the former ones. Tadpole developing into frog is an example of progressive Metamorphism whereas the herdmania larva undergoes retrograde Metamorphism.