how can I instantiate an object specifically at the intersection of a collider and a mesh

Hi everyone.
I would like to instantiate objects (rocks) along a mesh (mountain range). but it has to be only along the points where another objects collider meets the mesh.

my game is in 3D but I have illustrated the problem in 2D below.
I want to instantiate the object ONLY where there is intercept points.

the collider will always be perfectly circular.

Since I found the answer, I will post it here for anyone who was curious.
unity stores collision points when OnCollisionEnter() is called, through a type called ContactPoint.

private void OnCollisionEnter(Collision collision)
    {
        if (gameObject.tag == "mountain")
        {
            GameObject rockClone;
            foreach (ContactPoint contact in collision.contacts)
            {
                rockClone = Instantiate(rockPrefab, contact.point, transform.rotation);
               
            }
        }
    }