Butterstone - Australia

Butterstone from Australia is fossilized remains of stromatolites from over 2.5 billion years ago, during the Archean Eon of the Precambrian. During the Archean, the world was changing dramatically. This area of Australia was part of the Australian Craton, one of three smaller continents that make up modern day Australia. Along the edge of this continent in the shallow ocean, something amazing was happening – life. The earliest life on Earth are stromatolites from the Archean in Australia. Stromatolites are algal mounds that formed in the shallow marine waters. Changes in the world’s atmosphere allowed these organisms to appear. Stromatolites then were the major contributors to oxygen in our atmosphere, which allowed more advanced life to form Billions of years later, in the Cambrian Period (about 540-485 million years ago), the small continents of Australia started to collide, closing the oceans in between them. As the oceans closed, most of the oceanic crust was subducted under the continents, forming volcanoes similar to the Pacific Northwest of the United States today. However, some of the ocean crust was scraped up and deposited on top of the continent, as an ophiolite. Ophiolites include the oceanic crust as well as sediments that were deposited in the ocean. In this case, the stromatolites were on this ocean bottom and were scraped up onto the continent. . Due to the intense pressures associated with these collisions, the rocks are metamorphosed and altered. Many of the rocks have a green color to them in this region due to the presence of minerals such as chlorite. Other rocks that form from stromatolites include Pilbara Jasper, Jaspilite, Banded Iron Formation and Morgan Hill Poppy Jasper.