Web archival materials are not direct traces of the web, they are direct traces of crawlers. By design, the structure of web archives limits our collective capacity to explore the memory of the Web. These structural issues induce temporal discontinuities in the archives such as inconsistency, redundancy and blindness. In this paper, we address the question of re-injecting continuity within large corpora of web archives. We thus introduce the notions of persistences (series of time-stable snapshots of archived web pages) and continuity spaces (networks of time-consistent persistences). We demonstrate how-on the basis of a quality score-persistences can be used to select subsets of web archives within which in-depth historical analysis can be conducted at scale. We next propose to make use of a new visualization approach called the web cernes to graphically reconstruct the multi-level evolution of an archived web site. We finally apply our framework to study the archives of the firsttuesday movement: a constellation of networking web sites that acted in the interest of the economical growth of the web in the early 2000's.