d6dc8cf8_KS3_Ex___Earth_Science_On_Site__uitable_questions_at_this_site
[Acceptable responses] It is chemically and physically resistant to weathering; it is a large (heavy) piece not split by joints (or bedding as it is an igneous rock), and difficult to dislodge; it is impermeable and prevents water attacking the stonework below. It was also local to the site and cheap to transport here.
Why is this rock suitable for use as a capstone?
MEL/KS3/Ex - Earth Science On-Site