Well, you must be mistaken. That stuff looks as though it's been there for years.
3 seconds sound clip from Superman (1948) - Depths Of The Earth (Chapter 2).
You can hear this line at 00:14:56.079 in the Blu-ray version of the episode.
Quote context
[...]
- How about... way you came in?
- No chance. The shaft caved in.
- She went in there, and everything caved in.
- Is this the place that leads to where the men are trapped?
- Well, there's a shaft that'll lead down to that level.
- But that's what the young lady was headed for.
- And now you gotta dig through piles of dirt and rock.
- Well, you must be mistaken. That stuff looks as though it's been there for years.
- Oh, so you think I'm crazy too, huh? Well, I'll find someone to help. I'll find someone.
- This looks like a job for Superman. (2)
- What terrific force is this that Superman is fighting?
- What sinister danger menaces Clark Kent?
[...]