Unfortunately this wasn't a bottle dump. These artifacts were all excavated over a very large area over a period of nearly 6 hours. For example, the A. Hüpfel's Son's bottle was found directly in front of the remains of several old wooden pilings. My grandpa, who lived in the area as a child, told me people once fished here. So likely around the year 1890, a fisherman was on the pier and dropped the bottle into the water. And it remained there for 130 years. This is a photo of the bottle in situ in relation to the location of the old pilings:
A sure fire way to find old bottles (and other artifacts) is to find old pilings first and then explore around them. Every artifact you find there you can safely say was dropped by the person who last used the product. I find these artifacts more interesting and more insightful than "dump bottles", and I label them acordingly in my collection.
I do know of two very large old landfills that I dig on occasion. One capped in 1924, the other capped in 1913. I determined these dates through the latest dated artifacts I could find (coins, the remains of newspapers, and the lack of or presence of industrial chemicals such as gassoline. If you see an oily rainbow film in your landfill you know you are later in the 20th century, the cleaner the landfill the older as they didn't have as easy access to gasoline to burn the trash with yet).
