A Newcastle couple is reacting after finding a sinkhole on their property.
When Mark Korb woke up Sunday morning, he noticed the man-made pond on his property didn't look the way it did when he went to bed.
"This looks like the moon," said Korb, pointing at a sinkhole that caused a pond to drain onto his property.
A few years ago, Korb drained the pond with a pump, he said. The project took him seven days to complete.
The sinkhole emptied the pond much faster: "I would guess probably four to five hours for this whole area to drain," Korb said.
Now, he's trying to figure out what made the earth cave in on his property near Dutch Ravine, in an area that's commonly referred to as "Gold County."
A sinkhole is defined as movement of the ground downward, Sierra College Professor of Geology Alex Amigo said.
However, in this case, he said, it was probably not caused by groundwater dissolving material.
"There was such a lot of mining activity going on in this area in the past, that we never know when there was a man-made cavity underground," Amigo said.
There could have been a pre-existing fracture, or a fracture that formed -- ultimately, causing the sinkhole.
Korb is now looking into how to deal with the sinkhole.
He's also doing research on this history of his Newcastle property.