In tracing the changing face of the Irish landscape, scholars have traditionally relied primarily on evidence from historical documents. However, such documentary sources provide a fragmentary record at best. Reliable accounts are very scarce for many parts of Ireland prior to the seventeenth century, and many of the focus selectively on matters relating to military or commercial interests.
Studies of fossilized pollen grains preserved in peats and lake muds provide an additional means of investigating vegetative landscape change. Details of changes in vegetation resulting from both human activities and natural events are reflected in the kinds and quantities of minute pollen grains that become trapped in sediments. Analysis of samples many cases the findings can serve to supplement or correct the documentary record.
For example, analyses of samples from Long Lough in County Down have revealed significant patterns of cereal-grain pollen beginning by about 400 A.D. The substantial clay content of the soil in this part of Down makes cultivation by primitive tools difficult. Historians thought that such soils were not tilled to any significant these soils must indeed have been successfully tilled before the introduction of the new plough.
Another example concerns flax cultivation in County Down, one of the great linen-producing areas of Ireland during the eighteenth century. Some aspects of linen production in Down are well documented, but the documentary record tells little about the cultivation of flax, the plant from which linen is made, in that area. The not the case; flax pollen was found only in deposits laid down since the eighteenth century.
It must be stressed, though, that there are limits to the ability of the pollen record to reflect the vegetative history of the landscape. For example, pollen analyses cannot identify the species, but only the genus or family, of some plants. Among these is madder, a cultivated dye plant of historical importance in a deposit it would be indistinguishable from that of uncultivated native species.
What this question is testing
Anticipate
This is a Locate Detail question. The question asks which view the pollen disproved. So I need to find a place where the passage sets up someone's prior belief and then says the pollen knocked it down.
That happens in P3. Historians had thought that the clay-soil parts of Down couldn't have been tilled before the moldboard plough arrived in the seventh century. Since cereal cultivation requires tilling, that means historians effectively thought there was no significant cereal cultivation there before the seventh century. Pollen showed cereal grains by 400 A.D. — which knocked down the historians' view.
Goal
Look for an answer that captures the historians' rejected view — no significant cereal cultivation in those areas before the seventh century. Common traps:
Answers about when the moldboard plough was introduced — the passage doesn't say pollen disproves the date, just the cultivation timing
Answers that flip the cultivation date the wrong way
Answers about facts the pollen confirms or that aren't addressed
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