IELTS: 'Durdle Door and Dorset' - Erosion of a Headland

The diagrams below show the stages in the erosion of a headland.
Summarize the information by selecting and reporting the features, and make comparisons where relevant.
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The diagram shows the changes appearance of headland as a result of erosion.

The changing formation of headlands started from the hole which is formed in its bottom part as the result of wave attack. This bottom part is quite fragile as its component is too weak to restrain the power of the wave. As the wave hits the headlands gradually, the hole which looks like cave gets bigger and bigger. A big cave then forms an arch. Durdle Door and Dorset are two kinds of this erosion process. A continued attack strung out the roof of the arch collapses then separate a small part of headland which is called stack. It is caused by the ability of the water reach this higher position at high tide. Time by time, that stack becomes shorter by removing its top gradually then forms a stump beside it.

The pictures clearly show the continual process of reforming headland appearance which is mainly caused by erosion.

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  erosion.jpg
  

1. Your sentences, vocabulary, grammar, all that sound perfect and I think you've done a good job with this title. However, how's time? Did you handle the time effectively for this task ?

2. Not writing an overview. Your score will immediately drop if you do not write an overview clearly.

Diachronic maps/picts
Intro: here you should state what the maps/picts show
Overview: state what the direction of change is (is the city more modernized, has it turned to a tourist attraction/resort, etc)
Body: start with the most obvious changes and then try to cover all the changes.

Synchronic maps/picts.
Intro: here you should state what the maps/picts show
Overview: depending on what the purpose of those points are, give an opinion about which one may serve our purpose better.
Body: compare the two points