Continent Locations in the Past and Present

Question

The maps show the locations of continents at different times in Earth’s past.

There are five maps of the Earth's continents. The first map, labeled '250 million years ago', shows the continents joined together. The second map, labeled '200 million years ago', shows a small gap between the northern and central continents and another small gap between the central and southern continents. The third map, labeled '145 million years ago', shows the continents moving further apart. The fourth map, labeled '65 million years ago', shows a further separation between South America and Africa. The fifth map shows the continent locations at present day.

Constructed Response Question
This map shows the present-day locations of some of the continents. The shaded sections in South America and Africa represents two areas where similar sequences and ages of rocks are present.

A. Explain why similar rock sequences and ages support the claim that the continents have moved over time.

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Constructed Response Question
B. Look at the map of the location of continents 200 million years ago. Based on the map, identify which continent would be the most likely place to find rock sequences and ages similar to these, and explain why.

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Answer 1

A. Explanation of Similar Rock Sequences and Ages Supporting Continental Movement

Similar rock sequences and ages across continents provide strong evidence for the theory of continental drift, which posits that continents were once connected and have since moved apart. Here’s why:

1. Geological Connection: When continents were joined together, the geological processes that formed the rocks would have been continuous across the land mass. As the continents drifted apart, sequences of rocks that originated in the same location would still exhibit similarities, even after separation.

2. Matching Rock Types and Fossils: Similarities in rock types and the presence of identical fossils in different continents can indicate that these landmasses were once part of a single landform. For example, if a certain type of rock or specific fossil is found in both South America and Africa, it suggests that these continents were once connected.

3. Dating of Rocks: If the ages of rock layers in different continents match, this suggests that they formed during the same geological time period. This is important for supporting the idea that the continents were once contiguous before they drifted apart, as their geological features would align spatially and temporally.

In conclusion, the presence of similar rock sequences and ages across continents acts as evidence of past connections, showing that the continents have undergone significant geological movement over time.

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B. Identification of Likely Continent for Similar Rock Sequences and Ages

Based on the map of the continental locations 200 million years ago, the most likely place to find rock sequences and ages similar to those found in the shaded sections of South America and Africa would be in Antarctica.

Explanation:

1. Proximity in Past Positions: During the time represented in the 200-million-year-old map, Antarctica was situated relatively close to both South America and Africa. This close proximity means that the geological and ecological processes occurring at that time would have been more similar across those landmasses, producing comparable rock sequences and ages.

2. Geological Continuity: As part of the supercontinent Pangaea, the interactions between landforms and ecosystems shared across South America, Africa, and Antarctica would have contributed to the creation of similar rock formations. Therefore, there is a higher likelihood of finding similar rock sequences and ages in Antarctica than in continents that were more distantly located, such as Asia or North America.

In summary, the location of Antarctica near South America and Africa 200 million years ago makes it the most probable candidate for having rock sequences and ages that are similar to those found in the shaded areas of South America and Africa today.