Basalt with feldspar, Lake Michigans Left Coast, a blog by Elizabeth Fagan

Basalt with Feldspar Porphyry

Porphyry an igneous rock characterized by larger crystals embedded in a fine-grained mass. These are feldspar-basalt porphyry, with feldspar crystals in basalt. Repeated glacial episodes brought all kinds of rocks to my Lake Michigan beach in Ozaukee County, Wisconsin, like these, which originated in the Canadian Shield. Copyright, Disclaimer, Bibliography Elizabeth Fagan, Elizabeth Fagan, Elizabeth … Continue reading Basalt with Feldspar Porphyry

Basalt Ventifact

A ventifact is a rock that has been carved by wind-driven sand or ice crystals. This small basalt rock with the eerie, ghostlike pattern might be a ventifact or the result of water drip-drip-dripping over time. Copyright, Disclaimer, Bibliography