Can no Longer Access This Collapsed Mine

Many times when one explores these abandoned places, the adventure does not go as you have planned in your head. So when I finally decided to explore this mine it happened that adit had collapsed. There is a small hole that is all that is left of the adit. While expecting this hole to see if I can possibly open it up, no air was coming through. So this is telling me that there isn't another entrance. What a shame...