Old caves can sometimes be found by the following:

Look for different vegetation. Different plants like different places to grow. Caves are usually cooler and wetter than the surrounding area. They attract different plants. Since you are in an area with many caves and are looking for one that is now buried, look for the types of plants that normally grow around the obvious caves. Now look for the same kinds of plants in a rock pile or in a place without an obvious cave entrance.

Animals like caves for the same reasons as plants. Look for rock piles or other places that have a lot of fresh animal signs and burrows.

Infrared cameras can sometimes detect cave entrances that may be hidden by plants. The cooler rocks at the entrance will be the giveaway. Infrared can detect even slight temp. changes. I have heard that you can buy infrared film for a 35mm camera. Don't know how well it works, how much it costs, where to develop, or where to purchase infrared film.

Good Luck!!

Keith

P.S. If this helps and you find the treasure... remember me!