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14 www.DesertMessenger.com August 14, 2013 ADVENTURES WITH ROCKS Cannonballs, pottery and old plants By Jenn Jedidiah Free One of the most intriguing places we have been this summer is the Badlands of North Dakota. It also was a place that held many surprises for people like us who love rocks. We have been to the Badlands in South Dakota, in Utah, and in Nebraska, but the Badlands of Western North Dakota were different. Here in this arid grassland, where buttes of multicolored layers of sedimentary rock and volcanic tuff rise majestically above lush prairie, there are abundant examples of how diverse and fascinating rocks can be. The Paleocene landscape in the North Dakota of 60 million years ago was swampy bottom-land covered with thick vegetation and dense forests of sequoia, bald cypress, and other water-loving trees. Ancient rivers carried sediments of mud, sand, and silt off of the newly forming Rocky Mountains and deposited them in layers. Volcanoes in Montana and Idaho erupted and spewed huge amounts of ash into the swamps and rivers of Paleocene North Dakota. It was during these conditions that some of the most interesting rocks that I have ever seen were formed. And that's saying something, because I sure have seen a lot of interesting rocks in my lifetime. To begin with, fossils and petrified wood erode out of badlands buttes in abundance. Some sequoia and cypress stumps that have been found here are enormous specimens over 12 feet in diameter. While petrified wood can be found in many places, a type unique to the North Dakota Badlands is called Teredo-bored because it contains the fossilized remains of holes bored in the wood by little ancient clams called Teredos. Another interesting formation is the layer of lignite coal that is found throughout the badlands. Lignite coal is younger, geologically speaking, than harder, higher grade bituminous coal. It is the lowest rank of coal with the lowest energy content. It is formed from peat and plants, like other coals, but lignite coal is formed at shallower depths and with less heat and pressure than other coals. It is softer than bituminous coal and has a higher moisture content. It is also volatile. It burns easily and has a tendency to spontaneously combust. Lightning strikes and prairie fires often ignite seams of lignite coal. This tendency of lignite coal to combust creates another of the curious types of rock found in the North Dakota Badlands – a reddish rock called scoria. Scoria is baked and fused clay, shale, and sandstone. Scoria forms in thick layers or massive chunks of fused pieces of sandstone and clay. These reddish layers and masses of baked material formed in areas where seams of lignite coal burned. The heat produced from the burning coal baked nearby sediments into a natural form Got Drugs? Turn in your unused or expired medication for safe disposal Mon - Fri. 8am-5pm Quartzsite Police Department of brick. Scoria is also called clinker, probably due to the fact that the pieces clink like pottery when they hit against each other. In fact, broken pieces of scoria look, feel, and sound like pottery shards. By far the most interesting rocks we saw in the North Dakota Badlands were large spherical formations called Cannonball Concretions. Concretions are hard, compact masses of sedimentary rock formed when a mineral precipitation occurs around some type of nucleus, similar to how layers of minerals build up around a center core to form a pearl. Many shapes and sizes of concretions exist in the world, but the ones in North Dakota known as Cannonball Concretions are among the more unusual ones. Cannonball Concretions are made up of dissolved minerals of calcium carbonate cemented with siderite, or iron carbonate. Cannonballs up to three feet or more in diameter can be found in several places in Western North Dakota. The wide variety of shapes of concretions is The Gratitude Book Project releases its new summertime memory eBook and I'm in it! Get your FREE copy here: http://bit.ly/10Byp9q Shanana "Rain" Golden-Bear Co-Author http://thegratitudebookproject.com/ebook-download based on composition and cementing agent of the concretion, as well as the composition and hardness of the enclosing sediment. The Cannonballs are able to form in an enormous spherical shape because the soft bentonite clay sediment in which they form did not constrain the growth in any way. For photos, links, and more information about sites in North Dakota,visit our blog "Adventures With Rocks". Access our blog through the Media Link on the top tool bar of our website www.RocksInMyHead.biz. We carry an interesting and unique selection of petrified wood, rocks, minerals, meteorites, concretions, and fossils. We will be open in Quartzsite at A37 in Rice Ranch in the beginning of November, but meanwhile you can order by phone at 605-376-8754 or email at Jenn@RocksInMyHead.biz. Have a great summer and we'll see ya in the fall!