This image shows a cave formed not by underground erosion, but by the movement of two uneven formations toward and against each other, in this case forming a triangular opening which decreases towards the rear. Thus, it is not a proper cave at all.
There is no description on the back of this card.
Curiously, a search on the web shows that this is a popular description for narrow caves throughout the United States. Perhaps instead of cave this should be better labeled a rock shelter.
This image likely dates from the 1940’s.