Collagen plays an important role in many biological tissues, including skin, which, once dried and treated, forms parchment and leather. The structural alterations that occur in collagenous materials due to X-ray radiation damage, fluctuation of relative humidity, and mechanical deformation (with a special focus on historical parchment) are the focus of this thesis. The primary aim of this thesis is to investigate major structural changes to collagen within parchment when exposed to inappropriate levels of relative humidity during conservation treatments, and cyclic-humidity during long-term storage in archives, museums and libraries. This study led to the discovery that each parchment sample reacted to the application and removal of moisture in a different way, indicating the fundamental need to treat individual parchment documents as in-homogeneous materials. This thesis investigates the changes that fibrillar collagen undergoes and describes the creation of computational models capable of reproducing the X-ray diffraction patterns for collagen. Previous structural models have been created that sufficiently account for native collagen, however, models created as part of this thesis succeed where previous models have failed in explaining the X-ray diffraction patterns collected from damaged collagen. This study provided the opportunity to contribute towards a large-scale international collaborative project on the hugely important historical resource, the Domesday Book. X-ray diffraction was used to provide unprecedented analysis of Domesday Book samples, providing a structural survey at a molecular level. This analysis produced the conclusion that the majority of samples displayed the presence of collagen axial structure, and were generally of a degraded state as a consequence of the method used to source them the samples were scrapings from the surface, which was less intact than the bulk of the parchment.