Comment: 21:02 - 22:08 (01:06)
Source: Annenberg/CPB Resources - Earth Revealed - 17. Sedimentary Rocks: The Key to Past Environments
Keywords: "Cathy Busby-Spera", "sedimentary rock", "clastic sediment", "sedimentary structure", "Ridge Basin", "scour and fill", "water velocity", sandstone, sand, erosion, "depositional environment", "pebbly sand", "rip up fragment", "fluctuating current", "river channel"
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Our transcription: Another sedimentary structure known as "scour and fill" indicates that the velocity of the river fluctuated over time.
Within this sandstone bed we can see a sedimentary structure referred to as "scour and fill."
This is a surface running through the rock right here.
What we see is that the underlying sandstone has bedding that's truncated by this surface.
What this indicates is that flow was so strong during the initial deposition of this sandstone that the current eroded the previously deposited sands, and then as the current velocity slowed it began to deposit material.
First, it deposited pebbly sands and also deposited these rip up fragments of mud and then deposited sand above that.
So what we have in this scour and fill surface is evidence again of fluctuating current activity within the river channel.
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Geology School Keywords
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