PRIMARY SEDIMENTARY STRUCTURES A)Stratification Structures & Bedforms 1) Bedding & Lamination 2) Bedforms 3) Cross-lamination 4) Irregular stratification B) Bedding Plane Markings
BEDDING
Laminations < 1cm
Graded Bedding – Which way is up?
Bedforms & Cross-Stratification A) Ripple Marks – modern beach
Ripple Marks in Sandstone – Rock was formed on an ancient beach
2) Sedimentary Structures B) Cross Beds – the inside of Ripple Marks
Checkerboard Mesa – Zion National Park, Utah
Barchan Consistent wind Limited Sand Transverse Consistent wind Abundant Sand Parabolic “Blowouts” Coastal Dunes
Linear (Seif) Converging wind. Limited Sand Star Dunes Variable wind directions.
2) Sedimentary Structures C) Mud Cracks – Environment that periodically dries out