Which risk increased significantly when Inca terracing encountered unstable shale?

💡 Explanation

Enhanced water infiltration occurs in unstable shale geology; exceeding the terraces design leading to a rise in pore water pressure impacting internal frictional properties of terrace support. This increases slope instability via decreased shear strength, therefore terrace wall deformation risk increases rather than the alternatives linked to agricultural yields.

• Which outcome occurred when medieval instrument makers used brass alloys rather than iron when constructing astronomical astrolabes?
• Which structural weakness increased in Roman castra wall when built on clay-rich soil during seasonal rains?
• Which outcome arises during prolonged, repeated firing of early cast iron hand cannons?
• Which optical attribute was methodically studied using Alhazen's camera obscura, advancing understanding of vision?
• Which mechanical outcome occurred when applying Chinese cast iron to repeating crossbow trigger mechanisms?
• Which outcome reliably occurred when early cast iron crossbow trigger mechanisms fractured?