A landscape reacts to its environment, be it an explosive change from a volcanic eruption or a slower, gentler change over many millennia that carves a spectacular canyon. Earth keeps a passive archive of past events, quietly recording its history by “remembering” it as layers of sediment and folds of rock.1.3.1 Each change may be “remembered” by leaving a signal somewhere on Earth that, in turn, compounds with other such signals to form the remarkable strata-based archive that spans billions of years of Earth’s history, to later be interpreted by geologists.

Human history is recorded in much the same way: we make changes to Earth and affect natural processes, which in turn leave signals as layers of sediment.1.3.2 In fact, humans are creating and archiving such geologically unique signals that scientists have proposed it should mark a new epoch—the advent of the Anthropocene.1.3.3

As with any narrative, layers of complexity and dynamic change can become compounded as the story unfolds. For example, the development of a landscape can be gradational, it can form its own anthropogenic strata, or it may periodically have elements removed or changed.1.3.41.3.5 When observing an archive to collect information from Earth or human history, researchers sometimes find that overlapping histories are complex1.3.61.3.7 and obscure what has come before. Additionally, bias may stem from how physically accessible the material is.

Much geological theory focuses on understanding patterns and models, because we earth scientists often get to see very little of the puzzle. It can be likened to being given a handful of jigsaw pieces and no picture to follow. So, through using Occam’s razor combined with other deductive strategies, we have learned how to build a picture from the rocks that are accessible. Then, as more sites are uncovered and new analytical techniques are developed, ideas for explaining the geological archive are built upon, changed, and reinterpreted. There are uncountable possibilities for the number and variety of stories that can be read from the landscape, and geologists are constantly challenged with distinguishing between stabilized representation and evolving meaning. Is it possible for something to be solved conclusively, never to be changed? Some of the most exciting discoveries come from what we didn’t know that we didn’t know—so how could it be possible to interpret anything with finality?

When it comes to stabilizing evolving knowledge in the geological archive, we must look at the scale of the chosen narrative. A geologist seeking to finalize a precise reconstruction of an ancient landscape will carefully inspect evidence collected and collated and then define a concluding hypothesis. However, it may be that multiple hypotheses are possible, and the archive simply hasn’t yielded sufficient data for them to be refined any further. At the scale of one landscape, future insights will alter and refine the initial hypotheses, hence evolving the story.

Yet, when considering a global-scale context like the extinction of the dinosaurs, we find that a global signal of a meteorite impact has been archived. Stratigraphers recognize this signal with such certainty that it has been assigned as marking the beginning of a new Era, known as a Global Boundary Stratotype Section and Point (GSSP), a term that describes the globally recognized position at which one division of geological time becomes another. As such, a GSSP is widely considered to be a stable point in the geological record.

Right now, many deem us to have crossed from the Holocene into a new geological time period, called the Anthropocene, due to the surpassing of significant environmental thresholds and fundamental global alteration to planetary processes.1.3.8 As such, earth scientists consider the entire surface area of Earth to be covered with Anthropocene material, which represents the vastest scale of data, material, and cause-and-effect mechanisms that we, as scientists, have ever been able to directly observe from any time period.

However, how much of what we see today will become preserved in the geological archive? On land, sedimentary basins—areas of active subsidence where the land surface forms a slowly deepening bowl into which strata can accumulate—are the areas in which the geological archive will most likely become preserved. Yet, even collectively, such basins do not fully represent the climate and environments of the time, hence leading to a significant preservation bias.1.3.9 In light of this situation, geologists discuss “preservation potential” to understand the bias of the geological archive and what may become preserved into the future. For instance, we humans create holes to bury trash,1.3.10 hence increasing the probability of its longevity, and positively affecting its preservation potential. At this present moment, the ocean is the final resting place for much of what humans produce, but when looking toward a long geological future, most ocean crust is recycled about every 60 million years1.3.11—and so we see that even high preservation potential can be time limited.

The geological archive is temporally biased toward more recent rocks. We can find and compile a connected archive spanning about the past ~100 million years, but, beyond that, the records become more disconnected. Put simply, the longer rocks exist on Earth, the higher the chance they will be eroded and reworked into something new. When we look to the Precambrian Era,1.3.12 only a handful of sites exist for study, such that hypothesis testing becomes much more challenging. A popular adage in geology goes: “The further back in time we go, the more certain we seem to become.” This saying outlines how there is less scope for evolving meaning, and therefore how limited data allows stabilized meaning to prevail more readily, the further back in time we look.

In addition to inconsistency in completeness, rocks may be subject to alteration and contortion by vast environmental processes, such as tectonic activity. Rocks that once lay flat and were later crumpled or faulted into mountains tell the stories of their primary environment and its alteration since. Tectonic geologists, paleontologists, geochemists, and sedimentologists may work together on such an archive to tease the many perspectives and stories into the most rigorous narrative possible.

The passive archive that Earth continuously collates has been used by humans for energy sources, building materials, and much else. Additionally, humans preferentially choose archive materials that are of interest to study objectives or to add to collections. So, what sorts of materials do we preferentially keep for posterity? In paleontology, sites of exceptional preservation are studied and often preferentially archived, as they can provide the most stable hypotheses for the form and structure of extinct species.1.3.13 Beautiful fossils and minerals are sold at high prices to private collections and, as such, a bias exists toward the preservation of materials that are most rare.

Geologists have divided time to construct a stable framework upon which to understand the more irregular complexities of the stories they’re looking at, which furthermore exist at many scales, and these boundaries shift as evolving narratives are considered and extended.1.3.14 All of history (both human and geological) is a continuum, within which the outcomes of the past influence the present and continue to impact our future.1.3.15

Where will humankind’s most lasting signals reside, and how might the variable clarity or limitations of the past shape our understanding of the Anthropocene and affect our responses to its challenges? The past presents many clues as to how Earth reacts to change and how long landscapes can take to recover from impacts. However, today we find a deep need to combine and explore both physical and human archives, as the complexity of their joined narratives holds the key to the evolving future of humanity.1.3.16

In the key contribution that accompanies this pathway, “Active Archives,” I explore the diversity of relationships that can be formed with a collection and the importance of each. An archive is the sum of its parts, so through remembering that its curators and explorers are part of the joined system, the archive itself can be nurtured to its full potential. In my contribution, I focus on the geology archive held in the collection of the University of Leicester, considering who uses it and drawing upon insights from its curator, Vicky Ward, to explore the atmosphere that the collection creates. Finally, I reflect upon some of the more contemporary additions being contributed to such collections of archived geological material and consider our position in shaping the future record of today.