Fundamentals of geology I. (lithosphere) 1 1. The formation of the Earth 1
Fig. 2.7. Model of 3D cross stratifivcation
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- Fig. 2.8. Cross section of climbing ripples
- Fig. 2.9. ). Lenticular bedding
- Fig. 2.9. ). Flaser bedding
Fig. 2.7. Model of 3D cross stratifivcation Climbing-ripple cross stratification: The lamination produced when ripples move with a positive angle of climb is called climbing-ripple cross stratification. Net deposition during ripple formation produces an element of vertical motion of ripple crests as well as an element of horizontal motion. Climbing ripples are formed as a result; require net deposition, as in decelerating flows associated with river floods or turbidity currents. Depending on the relative magnitude of the climb angle vs. the stoss angle, climbing ripples can be classified as subcritically-climbing, critically-climbing, or supercritically-climbing (Fig. 2.8.). 
Fig. 2.8. Cross section of climbing ripples In the case of sand – clay alteration the following types of cross-bedding can be formed: Hummocky cross-stratification is a small-size form of cross-bedding usually formed by the action of large storms, such as hurricanes. It takes the form of a series of "smile"-like shapes, crosscutting each other. It is only formed at a depth of water below fair-weather wave base and above storm-weather wave base. They are not related to "hummocks" except in shape. This structure is formed under a combination of unidirectional and oscillatory flow that is generated by relatively large storm waves in the ocean. Deposition involves fallout from suspension and lateral tractive flow due to wave oscillation (Fig. 2.9.). Lenticular bedding: Formed during periods of slack water, mud suspended in the water is deposited on top of small formations of sand once the water's velocity has reached zero. It is classified by its large quantities of mud relative to sand. The sand formations within the bedding display a 'lens-like' shape, giving the pattern its respected name (Fig. 2.9.). Flaser bedding: It created when a sediment is exposed to intermittent flows, leading to alternating sand and mud layers. Individual sand ripples are created, which are later infilled by mud during quieter flow periods. These mud drapes are typically a minor constituent of the deposit; they can consolidate within three hours, protecting the underlying layer from erosion. Flaser bedding typically forms in high-energy environments (Fig. 2.9.). 
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