For as long as humans have walked the earliest trails and ventured forth from their caves,they have come up with a number of ways to record and communicate these paths to others. The most common marker we still see today is stack of stones known as a cairn. While there really is no need for a marker here since there isn't a trail to be found, you will find an example before you here. The cache is secured by the stones, but you shouldn't need to move any to retrieve the container.
Va gur anzr. Jngrecebbs zngpu ghor