A dry stone wall retaining is a type of retaining wall ,that is made of loose stones with no mortar. It is most commonly used in dry climatic zones.
Dry stone walls are durable and long-lasting structures, which create a solid foundation for homes and other buildings, as well as for roads and bridges. They can also be used to divert water flow.
The Benefits of Building a Dry Stone Wall Retaining in Your Garden
Dry stone walls have been around since the Iron Age, are built with stones that are not cemented together.
Dry stone walls are a great way ;to add an interesting pop of color to your garden. Dry stone walls can also be equally attractive on the inside as on the outside, giving you a chance to have more variety in your landscaping. The benefits of dry stone walls are endless!
A good determination of the location
The best way to make a dry stone wall is by using solid material for making its foundation. This will reduce the risk of collapse and save you time spent repairing damage caused by water seeping under the foundation.
Let's start working:

The foundation
Make a trench 6 inches deep, at least 20 inches wide, and spread about two inches of gravel.
The first section must be solid and even; because all the weight is at the base, ensuring the wall’s stability as the rocks hold together.
We tie them with a thread to the front of the wall and begin to lay stones.

It is possible to use an extended straight piece of wood to support the wall.
We begin to rock the saddle in a balanced way, position the stones in an appropriate manner, and move the stone to keep it in place. Next, we must choose the best surface from the front or back.
How can we choose the shapes of stones?
Not all rocks are alike, so they must be placed symmetrically, We carefully choose the right stones and try them in several ways, until we find the right position, the example in this picture.
We must use the mortar when we reach the last row of the wall (at a height of 40 inches) so as to increase the strength of its thickness; We choose thin and smooth stones to lay on the surface, to finally show us, a flat and beautiful shape.
Put the small stones in the appropriate spaces between the rocks
We also have to close the small gaps with stones suitable for them, and we do this after moving forward with steps to work. If we notice that the rocks are not well fixed, we can fix them by applying a little mortar.

Retaining walls are the best solution to stop soil erosion. As for the cost, it will not be large,depending on the length of the wall.