Red and White Bands
The Needles are a series of spires located to the southwest of Squaw Flat campground that surround the Chesler Park area of the Needles District. They are formed out of a resistant red and white sandstone layer called Cedar Mesa Sandstone which makes up most of the rock features in the Needles District. This 245 to 286 million year old layer was once a dune field on the eastern edge of a shallow sea that covered what is California, Nevada and western Utah today. Sand was blown in from this direction and formed the white bands in the Cedar Mesa Sandstone. The red bands came from sediment carried down by streams from a mountainous area near where Grand Junction is today. These layers of sand were laid down on top of each other and created the distinctive rocks seen today.
How Needles Form
Starting about fifteen million years ago, the Colorado Plateau was pushed up thousands of feet and rivers, such as the Colorado and the Green, cut down and carved deep canyons. Water, the primary force of erosion, eats away or weathers rock by attacking the cement holding the sand grains together. Moreover, during storms, rushing water knocks loose sand and rocks as it flows down washes causing additional erosion. The water naturally acts faster on areas of weakness within the rock, such as fractures and cracks. The Needles occur in an area with many fractures called joints.
How Joints Form
The joints were formed in two different manners. The first was the Monument uplift, which begins around the Needles District and trends slightly southwest all the way to Monument Valley. This uplift caused brittle, surface rock like the Cedar Mesa Sandstone to crack as it was bent upward, forming a set of joints in a northeast-southwest direction.
A thick salt layer underneath the Needles district, known as the Paradox Formation, is the second cause of joint formation. The salt is flowing slowly toward the Colorado River and dragging the overlying layers with it. As the upper layers became stretched, they also fractured into joints. This action created a set of joints running northeast-southwest. In the Needles area, these two joint sets meet and form square blocks of rock between the joints. As water widened the joints, the squares were sculpted into pillars and spires that are today the Needles of Canyonlands.
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