A lode is a rock body, not a layer of minerals. It's a vein or deposit of ore that occurs within a larger body of rock. While lodes can form in various ways, including deposition in stream beds, they are not *specifically* associated with stream beds.

Here's a breakdown:

* Lode: A body of ore within a larger rock formation.

* Stream Bed: The bottom of a river or stream, often containing sediments.

Lodes can form through various geological processes, including:

* Hydrothermal Activity: Hot fluids carrying dissolved minerals deposit them in fractures and cracks in rocks.

* Magmatic Activity: Minerals crystallize from cooling magma or lava.

* Metamorphic Processes: Existing minerals are altered or recrystallized under heat and pressure.

While lodes can be found in stream beds, they are not exclusively formed there.