graphiclogs
TRANSCRIPT
Graphic Logs of Sedimentary Rocks
I.G.Kenyon
Graphic Logs are a method used to record details of sedimentary successions to scale
The vertical scale is used to record bed thickness to scale, typically the scale will be between 1:10
(1 cm to 10cm) and 1:100 (1 cm to 1 metre)
The horizontal scale uses particle sizes of the Wentworth Scale, on the left hand side is Clay, then moving to the right is Silt, Sand, Granules, Pebbles, Cobbles and finally Boulders
A variety of symbols are used to indicate the presence of sedimentary structures including graded bedding, cross bedding, laminations, desiccation cracks,
ripple marks, flute casts and erosion surfaces
Symbols Used on Graphic Logs
Typical Glacial Sequence
Typical Fluvial (Meandering River Channel) Sequence
Desert Sequence
Deltaic Sequence – Coal Measures Cyclothem
Turbidity Current Sequence (Bouma Sequence-5 Units)
Exam questions using graphic logs of sedimentary sequences
The End