Near the St. Lawrence River, the low terrace has been covered with a layer of silty alluvia resting on clay. |
The best soils are the alluvia found on the terraced slopes and on the valley bottoms. |
In the 1980s, geologists in Moscow found several small diamonds and minerals, such as zircon, garnet, and corundum, in the alluvia of the River Karla. |