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Directional Structures. Show current direction Examples include such things as cross-beds, ripples, imbrications, flute casts Show current trend Examples include groove casts, parting lineation. Cross-bedding. Current Direction. Current from left to right. Ripple Marks.
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Directional Structures • Show current direction • Examples include such things as cross-beds, ripples, imbrications, flute casts • Show current trend • Examples include groove casts, parting lineation
Cross-bedding • Current Direction • Current from left to right
Ripple Marks • Asymmetric Ripples show current direction
Flute Casts • Found on the bottom of beds • scoop like structure
Parting Lineation • Yields current trend, not direction
Groove Cast • Yields trend of direction
Topping Indicators • Structures used to determine tops in sedimentary rocks include the following • Sole marks, Graded beds, Cross-beds, Symmetrical ripples, Mudcracks
Ripple Marks • Symmetric Ripples show tops
Graded Bed • Usually found in greywacke, caused by deposition of coherent mixtures of gravel, sand, mud and water
Mudcrack • Mudcracks occur in areas that are flooded and then dry out.
Sole Marks • Sole marks occur on the bottom of beds. Include flute and groove casts
Cross-bedding • Is truncated on the upper side of the bed