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Two major barriers hinder the holistic understanding of subsurface critical zone (CZ) evolution and its impacts: (a) an inability to measure, define, and share information and (b) a societal structure that inhibits inclusivity and creativity. In contrast to the aboveground portion of the CZ, which is visible and measurable, the bottom boundary is difficult to access and quantify. In the context of these barriers, we aim to expand the spatial reach of the CZ by highlighting existing and effective tools for research as well as the "human reach" of CZ science by expanding who performs such science and who it benefits. We do so by exploring the diversity of vocabularies and techniques used in relevant disciplines, defining terminology, and prioritizing research questions that can be addressed. Specifically, we explore geochemical, geomorphological, geophysical, and ecological measurements and modeling tools to estimate CZ base and thickness. We also outline the importance of and approaches to developing a diverse CZ workforce that looks like and harnesses the creativity of the society it serves, addressing historical legacies of exclusion. Looking forward, we suggest that to grow CZ science, we must broaden the physical spaces studied and their relationships with inhabitants, measure the "deep" CZ and make data accessible, and address the bottlenecks of scaling and data‐model integration. What is needed—and what we have tried to outline—are common and fundamental structures that can be applied anywhere and used by the diversity of researchers involved in investigating and recording CZ processes from a myriad of perspectives. Plain Language Summary: The "critical zone" is the zone of the Earth from treetops to belowground water. It is where crops are grown, water is drawn for drinking and industry, and waste generated by humans ends up. Understanding how deep this section of the Earth is, and how it is changing, is key to being able to determine how impactful changes in land use or climate will be to human systems. That said, it is difficult to get below‐ground information, and scientists in different subfields of the Earth sciences define the depth of the critical zone differently. Here, we describe the tools and language we use to make those decisions. We also note that Earth scientists are not a diverse group, which means we miss out on the ideas, solutions, and impacts that those from historically excluded groups might have to address the big problems humans must solve. To advance critical zone science, we need to broaden the physical areas we study, access to these sites, and the inclusion and sense of belonging of people studying them. We also need to measure deep into the Earth where we can, make our data accessible, and tackle scientific obstacles in integrating data and models. Key Points: CZ depth is defined by multiple processes key to human existence, yet is undermeasured and thus poorly understoodScientific jargon can make defining and communicating CZ processes difficult to stakeholders and even scientists in other fieldsLegacies in western science, upon which CZ science is based, can be countered to promote progress in the Earth sciences [ABSTRACT FROM AUTHOR]

Feedbacks between climate, erosion and tectonics influence the rates of chemical weathering reactions (1,2), which can consume atmospheric C[O.sub.2] and modulate global climate (3,4). However, quantitative predictions for the coupling [...]

We explore how rock properties and channel morphology vary with rock type in Last Chance canyon, Guadalupe mountains, New Mexico, USA. The rocks here are composed of horizontally to near horizontally interbedded carbonate and sandstone. This study focuses on first and second order channel sections where the streams have a lower channel steepness index (ksn) upstream and transition to a higher ksn downstream. We hypothesize that differences in bed thickness and rock strength influence ksn values, both directly by influencing bulk bedrock strength but also indirectly through the production of coarse sediment. We collected discontinuity intensity data (the length of bedding planes and fractures per unit area), Schmidt hammer rebound measurements, and measured the largest boulder at every 40-foot elevation contour to test this hypothesis. Bedrock and boulder minerology was determined using a lab-based carbonate dissolution method. High resolution orthomosaics and DEMs were generated from drone photos. The orthomosaics were used to map channel sections with exposed bedrock. The high-resolution DEMs were used to measure channel slope and hillslope relief. We find that discontinuity intensity is negatively correlated with Schmidt hammer rebound values. Channel steepness is higher where reaches are primarily incising through more thickly bedded carbonate bedrock. Where there is more thinly bedded sandstone rock exposed, channel steepness tends to be lower. Furthermore, the effect that rock properties have on channel morphology is confounded by sediment input from hillslopes. Thickly bedded rock units on surrounding hillslopes contribute larger sized colluvial sediment to the channels, and these reaches have higher ksn. Larger and more competent carbonate sediment armors both the carbonate and the more erodible sandstone and dampens the negative effect sandstone bedrock has on channel steepness. We believe that in the relatively steep, high ksn downstream channel sections slope is primarily controlled by the coarse alluvial cover. We further posit that the upstream low ksn reaches have a baselevel that is essentially fixed by the steep downstream reaches, resulting in a stable configuration where channel slopes have adjusted to lithologic differences and/or sediment armor. [ABSTRACT FROM AUTHOR]

The phenomenon of downstream fining has been attributed to both particle abrasion and selective particle sorting; the latter is generally considered to play the dominant role within resistant lithologies. It has been recognized that tributaries can disrupt fining patterns; however, few downstream-fining studies have considered the entire fluvial network structure. Here we combine a theory for selective transport with a model of river-basin evolution in order to simulate the dynamics of selective sorting throughout a drainage network. Previous numerical modeling studies of single-thread or braided channels have treated downstream fining as a phenomenon driven by differential deposition rates. We show, however, that in an eroding drainage network, downstream fining emerges as a natural dynamic adjustment to variable water, sediment, and energy inputs, even under conditions of uniform size distribution in sediment flux. Thus, although selective deposition and abrasion clearly can and do play a role in some fluvial systems, neither is necessary to produce downstream fining within a drainage network.

The article discusses the lack of representation of Latine scholars in the Earth sciences and the barriers they face, including discrimination, language barriers, and funding limitations. To address these challenges, the authors established the Code to Communicate (CoCo) program, which offers bilingual training in Python programming and science communication. CoCo recruits a diverse cohort of Latine participants and provides comprehensive training in Python libraries and SciComm strategies. The program has received positive feedback from participants, who reported increased confidence in coding and appreciation for the bilingual nature of the program. The article concludes by highlighting the professional development opportunities and transformative power of collaboration offered by CoCo. [Extracted from the article]