Step-by-step explanation:
Isostasy is a concept in geophysics that refers to the equilibrium in the Earth's lithosphere, where the crust and the uppermost part of the mantle "float" on the denser, semi-fluid asthenosphere beneath them. This concept helps explain the variations in elevations of Earth's surface features.
**Pratt's Views on Isostasy:**
- Pratt proposed the concept of isostasy in the mid-19th century.
- He suggested that variations in topography are compensated by differences in crustal thickness. Thicker crust would float higher on the semi-fluid asthenosphere, while thinner crust would sink lower.
**Airy's Views on Isostasy:**
- Airy also contributed to the isostatic concept in the 19th century.
- He extended Pratt's idea by considering variations in density within the crust. According to Airy, differences in rock density, rather than just thickness, could lead to isostatic adjustments.
- Airy's model considers that variations in elevation are compensated by differences in the density of crustal materials.
In summary, Pratt and Airy both played crucial roles in the development of the isostatic concept. Pratt focused on variations in crustal thickness, while Airy expanded the concept by considering density differences within the crust. Together, these ideas contribute to our understanding of how the Earth's lithosphere achieves a state of balance or isostatic equilibrium.