black and white gastropod slices in chazy limestone

ancient arc architectural arcuate background bedrock behind black blasting calcite calcium carbonate cement chambers champlain chazy chazyan chemical circular curves cuts dextral displays down evidence formation fossiliferous fossils gastropod geometric gray grey have hidden iapetus island lake left life lime limestone look marine mid millions mine mining new notice observe ocean ordovician paleontology patterned patterns plain profiles quarry replacement seas sedimentary shallow shells sinistral slices snail stepping stone study symbol symbolic their valcour ventral view warm white york