Deltas and The Evolution of Atolls
Instructions
https://www.google.com/earth/index.html
Part D of this exercise focuses on using Google Earth Pro (Google Earth (Links to an external site.)) to examine the characteristics of deltas and atolls.
Deltas can be classified according to the the dominant factor controlling their shape and evolution, whether river flow, wave action, or tidal range. These three factors collectively control the shape and configuration of deltas along coastline, notably the accumulation versus dispersion of sediment load from the river. As reference, the class materials for this topic describe the Mississippi as river-dominated and the Ganges as tide-dominated.
The following series of locations (name and latitude, longitude) provide links to major deltas helpful in answering the third question:
- Mississippi Delta, MS (29° 09′ 21″ N, 89° 15′ 40″ W)
- Huang-Ho (Yellow River) Delta, China (37° 44′ 42″ N, 119° 08′ 13″ E)
- Nile River Delta, Egypt (30° 57′ 22″ N, 31° 03′ 04″ E) – shown below
- Niger River Delta, Nigeria (5° 14′ 26″ N, 6° 16′ 18″ E)
- Ganges River Delta, Bangladesh (22° 34′ 11″ N, 89° 40′ 30″ E)
- Fly River Delta, Papua New Guinea (8° 28′ 49″ S, 143° 27′ 19″ E)
Example 1: The Nile River Delta, Egypt
The bonus question in this part of the exercise examines the evolutionary development of coral reefs associated with volcanic islands in the tropical Pacific Ocean, specifically focusing on atoll formation. It involves examination of the features of a number of Pacific islands ranging from volcanic islands with no reef development to islands with fringing reefs of varying size, and fully developed atolls in the Pacific, such as the following examples:
Example: Tuamotu archipelago
Question 1 5 pts
The following locations may be helpful in answering the question in this part of the exercise related to river-, wave-, and tide-dominated deltas:
- Mississippi Delta, MS (29° 09′ 21″ N, 89° 15′ 40″ W)
- Huang-Ho (Yellow River) Delta, China (37° 44′ 42″ N, 119° 08′ 13″ E)
- Nile River Delta, Egypt (30° 57′ 22″ N, 31° 03′ 04″ E) – shown below
- Niger River Delta, Nigeria (5° 14′ 26″ N, 6° 16′ 18″ E)
- Ganges River Delta, Bangladesh (22° 34′ 11″ N, 89° 40′ 30″ E)
- Fly River Delta, Papua New Guinea (8° 28′ 49″ S, 143° 27′ 19″ E)
Explain how the physical shape and characteristics of river-dominated deltas differs from tide- and wave-dominated deltas by use of images from Google Earth that help illustrate the distinctive features of different deltas.
A strong answer will designate locations according to name and latitude & longitude in Google Earth and describe how they typify the features of a particular type of delta. Specific reference will be made to aspects of the features in the image(s) – e.g. the shape and form of the delta coastline, the cloudiness of the waters at the mouth of the delta – that help to differentiate types of delta.
Question 2
Bonus Question (5 pt)
Explain the sequential process of atoll formation making explicit use of a series of three or more images from Google Earth to illustrate your answer, choosing examples of the evolutionary stages in the development of reefs that occur during the sequential transition of a volcanic island into an atoll.
A strong answer will designate locations with co-ordinates (latitude, longitude) providing visual complements in their Google Earth images that help illustrate the progressive sequence of coral reef development associated with atoll formation. A strong answer will focus on aspects of each image – e.g. features of volcanic islands, development from fringing reefs to barrier reefs and ultimately to atolls – that exemplify the progressive steps in the evolutionary process of atolls.