Sinkholes can range in diameter from a few feet to hundreds of acres. Their depths can be less than 1 foot to more than 100 feet. Some have vertical walls, others look like saucers or shallow ...

They often appear saucer-shaped but can look like cones, cylindrical potholes or deeper shafts upon formation. Sinkholes vary dramatically in size and depth – some span less than a metre, while ...

Some two to three billion years ago, low-oxygen, high-sulfur conditions — much like those in the sinkholes — in shallow, light-filled holes fueled the growth of photosynthesizing cyanobacteria ...