Lab - Isostasy and dynamics of the continental lithosphere - The PRATT model

Excerpt from the Official Bulletin:
Characterization of the continental domain:
continental lithosphere, relief, and crustal thickness (1-B-1)

Scientific Problematic:
In the first half of the 18th century, the geophysicist Pierre BOUGUER (1698 – 1758) observed that the gravity intensity he measured in mountainous areas was lower than the theoretical value calculated for this type of region. This difference was labeled as the negative Bouguer anomaly. It led to the idea that in mountainous areas, the relief, which represents an excess of mass, would be compensated in depth by a mass deficit.
This compensation would allow the rocks on the Earth's surface to rest in balance on deeper rocks. How can this balance be represented using a model?

Procedure:
The gravimetric anomalies highlighted by P. BOUGUER later led to two different models illustrating the balance between the lithosphere and asthenosphere (NB: unknown entities at the time): those of PRATT (1854) and AIRY (1855).
Using the model, the assembly corresponding to the PRATT model is created. The result is represented by a labeled and commented diagram.