Geologic_History

Geologic History Geologic History The Geologic History of Zion Canyon begins where the history of the Grand Canyon ends. The top layer of the Grand Canyon is the bottom layer of Zion National Park. The arid climate and sparse vegetation of the area allows the exposure of large portions of bare rock and reveal the park’s geologic history. Zion was a relatively flat region near sea level 240 million years ago. As. Sands, gravels, and muds eroded from surrounding mountains, streams carried these materials into the basin and deposited them in layers. The sheer weight of these layers that accumulated caused the basin to sink, so that the top surface always remained near sea level. As the land rose and fell as the climate changed, the depositional environment fluctuated from shallow seas to coastal plains to a desert of massive windblown sand. This process of sedimentation continued until over 10,000 feet of material accumulated. Lithification then occurred when mineral-laden waters filtered through the compacted sediments. Iron oxide, calcium carbonate, and silica acted as cementing agents, and with pressure over long period of time these deposits transformed into stone. Seabeds became limestone; mud and clay became zion, canyon, sandstone, sea, water, streams, rock, river, layers, uplift, top, level, lake, history, geologic, flat, feet, became, zion’s, years, within, waters, virginia, vertical, time, through, surface, slow, shale, sediments, sand, rose, relatively, process, plains, period, over, once, near, moving, mountains, million, layer, large, grand, forming, erosion, desert, deep, cutting