Sedimentology of Nile Floodplain and Desert Environments

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Questions and Answers

What does the high zirconium content of the sediments indicate?

Low aridity and reduced sand storms

High aridity and sand storms (correct)

Presence of Ethiopian flood water

Shift of the western Nile branch

What is supported by the ancient eye witness account of Ipuwer?

The eastwards shift of the western Nile branch

The sand encroachment from the Western Desert to the Nile Valley (correct)

The low rates of Nile channel movement during the Old Kingdom

The presence of Ethiopian flood water in the Nile Valley

What is indicated by the low ratios of diagnostic Blue and White Nile elements in the 4.2 cal kyr BP event?

Presence of secondary Nile distributary channels

Increased effects of Ethiopian flood water

Reduced effects of Ethiopian flood water (correct)

Higher rates of Nile channel movement during the Old Kingdom

What happened to the secondary Nile distributary channels during low Nile water flow?

They dried out in mid-winter Signup and view all the answers

What is the relationship between the secondary Nile distributary channels and the main Nile channel?

The secondary channels migrate faster than the main channel Signup and view all the answers

What is the significance of the XRF data for the 4.2 cal kyr BP event?

It indicates reduced effects of Ethiopian flood water Signup and view all the answers

What can be inferred from the heavy minerals assemblage in the Nile Valley sediments?

Mixing of Nile floodplain and desert wind-blown environments Signup and view all the answers

What is the significance of the water level declines in several lakes in the Nile catchment at 4.2 cal kyr BP?

It indicates reduced effects of Ethiopian flood water Signup and view all the answers

What is the current number of Nile channels bifurcating north of Cairo?

Two Signup and view all the answers

According to Stanley and Warne (1993b), what happened to the number of distributaries around 6000 years ago?

It reached a maximum Signup and view all the answers

What was the average subsidence rate measured in one study using radar satellite data?

7 mm/yr Signup and view all the answers

During the pre-dynastic period, how many Nile branches were there?

Seven Signup and view all the answers

What is believed to have influenced subsidence within the study area, according to one study?

Tectonics and groundwater extraction Signup and view all the answers

What was the maximum subsidence velocity measured in another study using radar satellite data?

6-8 mm/yr Signup and view all the answers

What was the source of water that fed Lake Faiyum?

Nile run-off through the Bar Yussef Signup and view all the answers

What is the primary component of Sequence 'II' in the Nile Delta?

Bluish-black silty-clay to clayey silt Signup and view all the answers

What feature defines paleo-shorelines at 44-46 meters in the Faiyum region?

A series of ridges Signup and view all the answers

What is the time period represented by Sequence 'I' in the Nile Delta?

38-12 kyr BP Signup and view all the answers

What is the characteristic of Sequence 'IIb' in the Nile Delta?

Brown-grey in color and predictable grain size Signup and view all the answers

What is the result of the overtopping of levees and the development of a wide floodplain during the late Holocene?

Development of Sequence 'IIb' Signup and view all the answers

What method was used to investigate the Late Quaternary sediments of the Nile Delta?

All of the above Signup and view all the answers

What is the characteristic of the modern aeolian Member in the Nile Delta?

Marks the end of the fluvial-dominated delta Signup and view all the answers

What is the dominant feature of the coastal region of the Nile Delta?

Fluvial-dominated delta Signup and view all the answers

How many relevant core records were provided by a survey of the published literature within the fluvial zone of the Nile Delta?

1640 Signup and view all the answers

Study Notes

Nile Valley and Floodplain

The heavy minerals assemblage in the Nile Valley reflects mixing of Nile floodplain and desert wind-blown environments.
High zirconium content in sediments indicates high aridity and sand storms, leading to sand encroachment from the Western Desert to the Nile Valley.
An ancient eye witness account by "Ipuwer" mentioned the desert claiming the land and the lands being injured.

Nile Channels and Distributaries

During the Old Kingdom, there was an eastwards shift of the western Nile branch and a westward shift of the main Nile channel.
Secondary distributary channels migrated faster than the main channel due to their relatively higher elevation and drying out in mid-winter during low Nile water flow.
There are different estimates for the rate of Nile channel movement during the Old Kingdom.
The number of distributaries reached a maximum around 6000 years ago and has gradually declined since then.
Currently, there are only two Nile channels, Rosetta and Damietta branches, bifurcating ca. 20 km north of Cairo.

Sediment Cores and Sequences

Late Quaternary sediments of the Nile Delta were intensively investigated through archaeological excavations, drilling of shallow cores, and radiocarbon dating.
A survey of published literature provided 1640 relevant core records within the fluvial zone of the delta.
The sediments comprise three sequences: Sequence "I" (late Pleistocene—ca. 38–12 kyr BP), Sequence "IIa" (bluish-black silty-clay to clayey silt with high organic matter and peat layers), and Sequence "IIb" (brown-grey in color, less rich in organic material).
Sequence "IIb" represents overtopping of levees and the development of a wide floodplain during the late Holocene.

Subsidence and Radar Satellite Data

Radar satellite data has been used to measure subsidence on the Nile Delta, with average subsidence rates of 7 mm/yr.
Subsidence is influenced by groundwater extraction, tectonics, and possibly the subway system running under the city.
Another study measured maximum subsidence velocities ranging from 6 to 8 mm/yr on the north-western portion of the delta.

Faiyum and Lake Fluctuations

Fluctuations in Nile flooding controlled the levels of the lake in the Faiyum, which affected ancient settlement patterns.
A series of ridges along the western edge of the depression define paleo-shorelines at 44–50 m above sea level.

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Description

Quiz about the mixture of Nile floodplain and desert wind-blown environments, sedimentological characteristics, and interpretation of Landsat and Google imagery.