After the terrain is defined, the terrain depth is seen as a mass by giving a thickness with terrain/depth feature.
Location of Terrain/Depth Feature
Select the terrain you want to give depth, click the right button of the mouse and click the Properties row from the menu that opens .
Select the terrain and click the right mouse button. Click the Properties line with the left button from the menu that opens.
In the dialog that opens, check the Soil base option at the bottom.
Enter the value you want in the active depth line.
Assign a material that you find suitable for the land in the material section.
After this process, the land will appear as a mass on the 3D screen.
Terrain before Terrain/Depth is given
Marking the soil base feature and giving 100 cm as the depth value
Terrain after Terrain/Depth has been given