Why are the Archean and Proterozoic Eras not divided into smaller ...

[beccaep]

Why are the Archean and Proterozoic Eras not divided into smaller units like the Cenozoic Era?
 
  What will be an ideal response?

Question 2

Compare the doctrine of catastrophism with the doctrine of uniformitarianism.
 
  What will be an ideal response?

[aloop]

Answer to Question 1

Answer: This part of Earth's history is commonly called the Precambrian. The Precambrian occurred so long ago (4 billion years before the Cambrian) that not much detail is known from this time. The further back in the rock record/time you look, the more fragmented the record and clues become.

Answer to Question 2

Answer: Catastrophism was an early idea about the nature of Earth and was based on religious traditions and notions of great catastrophes. Essentially, it posited that (a) the Earth was very young (less than 10,000 years), and that all geologic change happened rapidly through violent catastrophes. In contrast, James Hutton emphasized that the same slow processes have acted over great spans of time and are responsible for Earth's rocks, mountains, and landforms. This similarity of processes over vast spans of time led to this principle being called uniformitarianism. In other words, physical laws were uniform over time, and most geologic change was gradual, not catastrophic.

[beccaep]

TYSM

[blakcmamba]

Excellent