Agates from the Niagara Escarpment represent the northernmost agates in the USA, which originate from sedimentary rocks. The Niagara Escarpment forms an elongated geological stage trough Ontario, Michigan, Wisconsin and Illinois, as well as trough a part of Canada. Their oldest rocks originate from the silurian age. The highest layer is a dolomitical limestone.

Near to Stevens Point a quarry is situated where these sedimentary agates can be found. Unfortunately the size is very limited. Bigger ones from this strata can be found in Michigan, in the Scotts quarry.