▶ Your Answer :
The reading passage contends that the origin of theses forts with their distinctive stonework can be explained by three theories. On the other hand, the lecturer makes counterargument with three point.
First, the writer acclaims that signal fires led to vitrification. This supported by the fact that the vitrified stones are most common on the upper parts of the walls. However, the professor pointed out that entire upper parts of walls were vitrified. If walls were used to signal fires, only a few walls would have been vitrified.
Second, the author asserts that lightning caused the stones of forts vitrified. In addition, lightning accounts for the uneven appearance of the walls. In contrast, the lecturer refutes the argument, saying that if lightning had made the stones vitrified, lightning must have heated on one spot over and over. It was virtually impossible that lightning strikes many times. Moreover, the uneven appearance was natural given that the forts was built long time ago.
According to the reading, forts were built using volcanic rock which is already vitrified. The ancient residents of Scotland used volcanic rock. On the other hand, the speaker pointed the absence of record of eruption, which means that people should have transported volcanic rock from far area. However, There is no proper read to transport heavy materials. Thus, residents should have used the local material in building forts |