I Forgot the Name of That ___! discussion

I just thought of another book I remember reading back in the day:

It was a Dr. Cooper or Mr. Cooper that was an explorer. He had a daughter and a son and they go to this place that none of the locals would go to. There was a hole in the middle of a dead sandy perfect circle. Not even animals or bugs would cross the (what seemed to be) burnt edges of this really massive circle (like miles wide). They went into it and then in the end found this huge impenetrable door which they needed a key to get in. This door was on the cover of the book I think? I believe there were evil spirits behind the door and the managed to shut it with a lot of work?

Anyone else remember reading about this book? I think there might have been more books in the series?

Thanks!

Sorry...it clicked after pushing send. Frank E. Peretti. The Door In The Dragon's Throat