Broken Glass In Crawlspace Of My Old 1900 House…Why?

I recently just purchased an old farm house built in the 1900’s. The floor is being raised, but we are finding a lot of broken glass and animal skulls all over the crawlspace…more in some areas than others. The skulls are actually what we think are deer or horse…they are big. Our question is how did they get down their…..someone had to have put them their.
Is their some kind of tradition or superstition that goes along with this?