2D infinite runner obstacle generation?

Hi Unity,
I am developing a game that has 2 types of obstacles: One that you have to jump over and one that you have to slide under. How could i generate them randomly without them generating on top of each other (they must be far apart or else the player wont have a chance to avoid them and survive).
Thanks in advance!

Use this for a concept than elaborate with me and we can work towards your goal a little more;

                           if (!obj)
				obj = Instantiate(object,Vector3(Random.Range(spawnRange.x,spawnRange.y),transform.position.y,transform.position.z + 20),transform.rotation);
			else
				obj = Instantiate(object,Vector3(Random.Range(spawnRange.x,spawnRange.y),transform.position.y,obj.transform.position.z + options.obstacleSpacing),transform.rotation);