What was the nature of the earth surface initially?
Initially, the earth was mostly in a volatile state during its primordial stage. The planet earth was a barren, rocky and hot object with a thin atmosphere of hydrogen and helium.
Due to gradual increase in density, the temperature inside increased. This caused heavier materials like iron to sink towards the centre and lighter ones to move towards the surface. With time, it cooled further and solidified into a smaller size, leading to the development of the outer surface in the form of a crust.
Explanation
The textbook context clearly describes the initial nature of earth's surface in two key sections. First, it states that 'the earth was mostly in a volatile state during its primordial stage.' Second, it explicitly mentions that 'the planet earth initially was a barren, rocky and hot object with a thin atmosphere of hydrogen and helium.' The context also explains how the layered structure developed through differentiation - heavier materials sank to the centre while lighter ones moved to the surface, eventually forming the crust.