| Date | Marks available | 6 | Reference code | .2.bp.3 | |
| Level | SL and HL | Paper | 2 | Time zone | |
| Command term | Explain | Question number | 3 | Adapted from | N/A |
Question
The map shows the age of oceanic crust.
[Source: Computerized digital images and associated databases from the National Geophysical Data Centre, National Oceanic and Atmospheric Administration, U.S. Department of Commerce]
Referring to the map, identify the type of plate boundary shown on the map at:
(i) A
(ii) B.
State the age of the oceanic crust at C shown on the map.
Using an annotated diagram only, explain why the age of oceanic crust changes with distance from the mid-ocean ridges.
Referring to specific nations, discuss the geopolitical issues that arise over ocean areas.
Markscheme
The boundary type at A is constructive or divergent [1 mark] and at B is destructive or convergent (accept subduction but do not accept collision zone) [1 mark].
The age of the crust at C is between 141.9 and 156.8 [1 mark] million years BP [1 mark]. Any number within the range is acceptable; only answers within this range can gain the second mark.
Candidates must use an annotated diagram to answer this question. No credit should be given for any information that is written separately below the map unless it is clearly related to it by means of arrows or a key. As a general rule 3 marks should be awarded for the quality and appropriateness of the diagram and 3 marks for the quality of the annotations. This balance can be adjusted if exceptional quality is found in either of these two parts.
In good answers the annotations should include new crust being created at constructive plate boundaries which moves away from the boundaries as part of the process of sea-floor spreading. With distance the age of crust increases as a result of this divergent process.
As populations and resource demand increase, and standards of living increase, more pressure is placed on peripheries and boundary zones and the ownership of them. There are many areas of the world where issues arise as a result of oceanic territorial disputes. These issues may be a product of sovereignty rights, resource need, military advantage, historical situation or any other valid reason.
In some cases this may disadvantage nations who are not allied to a particular group or are members of an economic agreement and this may serve to impoverish nations or create tension.
Responses that are discursive are likely to be credited at bands E/F.
Marks should be allocated according to the markbands.
