North-central Andes Research Articles

Controls on topography and erosion of the north-central Andes

Abstract We present 17 new 10Be erosion rates from southern Peru sampled across an extreme orographic rainfall gradient. Using a rainfall-weighted variant of the normalized channel steepness index, ksnQ, we show that channel steepness values, and thus topography, are adjusted to spatially varying rainfall. Rocks with similar physical characteristics define distinct relationships between ksnQ and erosion rate (E), suggesting ksnQ is also resolving lithologic variations in erodibility. However, substantial uncertainty exists in parameters describing these relationships. By combining our new data with 38 published erosion rates from Peru and Bolivia, we collapse the range of compatible parameter values and resolve robust, nonlinear ksnQ–E relationships suggestive of important influences of erosional thresholds, rock properties, sediment characteristics, and temporal runoff variability. In contrast, neither climatic nor lithologic effects are clear using the traditional channel steepness metric, ksn. Our results highlight that accounting for spatial rainfall variations is essential for disentangling the multiple influences of climate, lithology, and tectonics common in mountain landscapes, which is a necessary first step toward greater understanding of how these landscapes evolve.

Crafting cosmopolitanism: Ceramic production and exchange during Wari imperialism (600–1000 CE)

The expansive Wari state of the Middle Horizon (600–1000 CE) was the first political structure to unify the south-central and north-central Andes. Simultaneously, Wari’s political and cultural influence was not uniform across the diverse populace whom they sought to integrate. In this paper, we propose that a localized view of cosmopolitanism is apt for analyzing heterogenous Wari politics and its impacts on social identities and economies. Rather than assuming cosmopolitan worlds were constituted only in elite contexts, we consider how Wari cosmopolitanism was born out of the everyday and influenced by the localized practices, concerns, and motives of differing groups. We apply this perspective to the study of ceramic production and exchange across disparate Andean regions. Here we integrate new laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) data with previously published data to assess ceramic compositional variability across three regions: Ancash, Arequipa, and Moquegua (N = 189). This new sample set consists of Wari finewares (e.g., Viñaque, Ocros, Chakipampa), Wari-related or emulated materials, local Middle Horizon styles with Wari influenced motifs, and Middle Horizon plainwares. Previous compositional studies suggest that artisans in the Wari heartland of Ayacucho and the Moquegua province crafted imperial ceramic styles for elite consumption within centralized production zones. However, our findings indicate that, in Ancash and Arequipa, the production of Wari emulated pottery drew upon established local knowledge of clay sources. Data suggest that local groups used clays with similar geochemistries to produce both fine and plainwares. Simultaneously, these production strategies were complemented by the influx of Wari finewares from other regions, but the consumption of these prestige goods was not necessarily restricted to elite centers. We thus argue that Wari cosmopolitanism was constituted by local and global processes that were part of everyday life. Moreover, ceramic production and exchange was not necessarily controlled by Wari elites in all contexts nor was it part of an imperial wealth-finance system.

Description of Bothriurus mistral n. sp., the highest-dwelling Bothriurus from the western Andes (Scorpiones, Bothriuridae), using multiple morphometric approaches.

We describe Bothriurus mistral n. sp. (Scorpiones, Bothriuridae) from the Chilean north-central Andes of the Coquimbo Region. This is the highest elevational discovery for Bothriurus in the western slopes of the Andes. This species was collected in the Estero Derecho Private Protected Area and Natural Sanctuary as part of the First National Biodiversity Inventory of Chile of the Integrated System for Monitoring and Evaluation of Native Forest Ecosystems (SIMEF). Bothriurus mistral n. sp. is closely related to Bothriurus coriaceus Pocock, 1893, from the lowlands of central Chile. This integrative research includes a combination of traditional morphometrics and geometric morphometric analyses to support the taxonomic delimitation of the species.

Testing Phylogeographic Hypotheses in Mepraia (Hemiptera: Reduviidae) Suggests a Complex Spatio-Temporal Colonization in the Coastal Atacama Desert

Simple SummaryMepraia is a blood-sucking bug endemic to Chile and a vector of the parasite that causes Chagas disease. Different colonization routes have been suggested for this bug; therefore, we tested different colonization routes using DNA sequences and bioinformatics approaches to select the most probable route. Our results suggest that, after the split of Triatoma, Mepraia divided into two main groups ~2.1 Mya. The northern group would have speciated between 1.7–1.4 Mya, giving rise to M. parapatrica, M. gajardoi and to a new, still undescribed lineage (Mepraia sp.). The southern group formed M. spinolai ~1.68 Mya. We suggest that Mepraia originated from the north-central Andes due to the last Andes uplift and hyperaridity. The hyperarid cycle would have separated the southern and northern groups. Then, within the northern group, colonization would have occurred from the centre to the north and south through corridors influenced by Pleistocene climatic changes. The habitat colonized by the southern clade led to only one species (M. spinolai). Fluctuations in climatic changes probably influenced speciation strongly in this kissing bug in the Atacama Desert.Mepraia is a genus (Triatominae) endemic to Chile and a vector of Trypanosoma cruzi. Alternative phylogeographic hypotheses have been suggested for Mepraia. We tested different colonization routes hypothesized using mitochondrial sequences and phylogeographic approaches to select the best-supported hypothesis. Our results suggest that, after the split from the sister genus Triatoma at ~4.3 Mya, Mepraia formed two main clades at ~2.1 Mya. The northern clade diverged from Mepraia sp. ~1.7 Mya, giving rise to M. parapatrica and M. gajardoi about ~1.4 Mya. The southern clade originated M. spinolai ~1.68 Mya. We suggest that Mepraia had an origin in the north-central Andes along with orogenic processes, reinforced by hyperaridity during the Pliocene. The hyperarid cycle would have separated the southern and northern clades. Then, in the northern clade, dispersal occurred north and south from the centre through corridors during the Pleistocene Climatic Oscillations. Climate changes may have induced a major speciation process in the Atacama Desert, while the more homogeneous habitat colonized by the southern clade led to only one, but structured, species.

Shonquilpampa: Camelid Pictographs of the Cordillera Blanca, Perú

Shonquilpampa is one of the numerous U-shaped narrow glacial valleys of the Cordillera Blanca mountain system in Peru’s north central Andes. The valley floor has enormous granodiorite boulders detached from glaciers. Some of these boulders contain painted camelid pictographs that indicate the importance of the animal as an economic resource for hunters and herding groups. Scenes of camelid hunting and large herds depicted in red appear in the same panel, while apparently, humans play a minor role. However, a band of hunters is shown exclusively in another rock face. The dominant figure, an elongated and tall camelid, is the focal point of the panels. Dynamic hunting scenes are associated with Archaic styles, while static herds are related to post-Archaic developments. The images suggest a gradual transition from wild to domesticated camelids in the mountains of Ancash.

A new species of Lepanthes (Orchidaceae: Pleurothallidinae) with rabbit ear-like petals endemic to Colombia

A new species of Lepanthes from the department of Antioquia apparently restricted to the north-central Andes of Colombia is described and illustrated. The new species is similar to L. alcicornis; however, it can be easily distinguished by the transversally lobulate petals that resemble the ears of a rabbit, the reniform lip with sub-oblong basal lobes surrounding the column, and the absence of an appendix on the lip.

Is there a Central Andean Linguistic Area? A View from the Perspective of the “Minor” Languages

In this article, I reconsider the evidence for a Central Andean linguistic area. I suggest that there is no evidence for a clear-cut linguistic area comprising the entire Central Andes narrowly defined, and that perceived homogeneity is partially due to an overemphasis on the largest and surviving Central Andean language families, Quechuan and Aymaran. I show that none of the other Central Andean languages known sufficiently well match their typological profile to a high degree. I make a contribution to a more adequate picture by discussing some typological aspects tentatively recoverable for the extinct and poorly documented languages of the North-Central Andes. These suggest that the North was the site of linguistic traits contrasting with those of Quechuan and Aymaran.

Mitochondrial phylogeography of kinkajous (Procyonidae, Carnivora): maybe not a single ESU

AbstractKnowledge of how a species is divided into different genetic units, and the structure among these units, is fundamental to the protection of biodiversity. Procyonidae was one of the families in the Order Carnivora with more success in the colonization of South America. The most divergent species in this family is the kinkajou (Potos flavus). However, knowledge of the genetics and evolution of this species is scarce. We analyzed five mitochondrial genes within 129 individuals of P. flavus from seven Neotropical countries (Mexico, Guatemala, Honduras, Colombia, Ecuador, Peru, and Bolivia). We detected eight different populations or haplogroups, although only three had highly significant bootstrap values (southern Mexico and Central America; northern Peruvian, Ecuadorian, and Colombian Amazon; and north-central Andes and the southern Amazon in Peru). Some analyses showed that the ancestor of the southern Mexico–Central America haplogroup was the first to appear. The youngest haplogroups were those at the most southern area analyzed in Peru and Bolivia. A “borrowed molecular clock” estimated the initial diversification to have occurred around 9.6 million years ago (MYA). All the spatial genetic analyses detected a very strong spatial structure with significant genetic patches (average diameter around 400–500 km) and a clinal isolation by distance among them. The overall sample and all of the haplogroups we detected had elevated levels of genetic diversity, which strongly indicates their long existence. A Bayesian Skyline Plot detected, for the overall sample and for the three most significant haplogroups, a decrease in the number of females within the last 30,000–50,000 years, with a strong decrease in the last 10,000–20,000 years. Our data supported an alignment of some but not all haplogroups with putative morphological subspecies. We have not discounted the possibility of a cryptic kinkajou species.

Inscrição, local e memória: arte de uma roca palimpsesto e a evolução das paisagens sociais andinas durante o Período Formativo (1500 - 200 a. e. c.)

As more than a means of recalling, memory is an active cultural creation and landscape inscriptions construct memories by locating place-based historical narratives. To model memory in terms of engagement with a place through inscription, this study focuses on a complex palimpsest petroglyph panel at the site of Kiñan Tanka, which is situated in the highland north-central Andes. Photogrammetric modeling and vector renderings of Kiñan Tanka’s panel are analyzed to identify the microstratigraphy of its motifs. These data are paired with recently-acquired excavation data from three nearby rock art sites to reveal a tradition of incised petroglyphs that covered approximately 1300 years (1500 - 200 BC). The spatio-temporal relationships of Kiñan Tanka’s iconography are considered within its context as a venerated place and a threshold between distinct worlds during the Formative Period.

Detrital-zircon geochronology and provenance of the El Oro Metamorphic Complex, Ecuador: Geodynamic implications for the evolution of the western Gondwana margin

The El Oro Metamorphic Complex (EOMC) in SW Ecuador has been the subject of debate for several decades. While previous studies have focused on the metamorphic and deformation history of the complex to determine its geodynamic evolution, the pre-metamorphic history and its association to units in the north-central Andes remains poorly understood. Here we present a U-Pb detrital zircon provenance study to provide insights into the depositional history and the geodynamic setting of the EOMC. Our results imply that the southern portion of the EOMC (the Tahuín division) is composed of an older Palaeozoic (pre-Famatinian) sequence in the south (El Tigre unit; c. 525-510 Ma), and younger Palaeozoic (post-Famatinian) sediments in the central and northern parts of the Tahuín division (La Victoria and La Bocana units; c. 370-360 Ma). The provenance of the sedimentary sequences correlates with autochthonous post-Famatinian units (440–340 Ma) in the Eastern Cordillera of Peru and the southern Cordillera Real of Ecuador. Importantly, our data provide evidence for a genetic link between the northernmost (the Birón Complex) and the southern (La Victoria and La Bocana units) sequences of the EOMC. Post-Famatinian sediments were identified in the Birón Complex (Palenque Mélange division; c. 400-390 Ma) and are derived from the same sedimentary sources as the sediments of the southern EOMC. The depositional range of post-Famatinian sediments in the EOMC is therefore constrained to c. 400-360 Ma. Furthermore, we identified a Middle to Upper Triassic sedimentary sequence in the Birón Complex (Limón Playa unit; c. 240-215 Ma) that likely developed contemporaneously with c. 240–217 Ma syn-rift continental epiclastics of the Mitu Group in Peru. Combined, these new detrital zircon data demonstrate that the existing lithostratigraphic scheme is erroneous and that three temporally distinct sequences are present in the complex, with the oldest units in the south and the youngest in the north. Separation of the southern EOMC (the Tahuín division) from the autochthonous Gondwanan margin of the north-central Andes was likely due to a change in the regional subduction direction from SE to ENE at c. 140Ma, with the southern EOMC rotating in a clockwise direction into its present-day E–W orientation. This rotation also could have been a response to the first accretion of proto-Caribbean terranes, such as the Alao–Quebradagrande terrane at c. 120 Ma, with a maximum age for rotation constrained by the earliest sediments (Early (?) to Middle Albian, c. 113-105 Ma) arriving into the Celica-Lancones Basin, which unconformably overlie the Tahuín Group in the southern EOMC.

Over Rock and Under Stone: Carved Rocks and Subterranean Burials at Kipia, Ancash, AD 1000 – 1532

AbstractResearch in the Andes has yielded evidence for a complex association between settlement sites and mortuary monuments, tied to concepts of death, ancestor veneration and water. The Huaylas-Inca and later Spanish colonial site of Kipia in the Cordillera Negra of the Ancash Highlands, North-Central Andes is a multi-faceted site, that contains a small settlement core, and a cosmological centre which includes carved rocks (huancas), niches and offerings. This, in turn backs onto a necropolis composed of a series of subterranean tombs (pukullo). In association, these features directly reference the surrounding agro-pastoralist landscape. In particular they evoke neighbouring lakes as possible foci of ethnogenesis or pacarinas. The relation between ceremonial sites and cemeteries is crucial to understanding Andean concepts of death and renewal. In this article, alongside a detailed description of the site, we provide a preliminary analysis of the contents of one of the pukullo. In turn, these results are placed within their landscape context to discuss issues related to sacrality, water and death.

Kinematics, Exhumation, and Sedimentation of the North Central Andes (Bolivia): An Integrated Thermochronometer and Thermokinematic Modeling Approach

AbstractQuantifying mountain building processes in convergent orogens requires determination of the timing and rate of deformation in the overriding plate. In the central Andes, large discrepancies in both timing and rate of deformation prevent evaluating the shortening history in light of internal or external forcing factors. Geologic map patterns, age and location of reset thermochronometer systems, and synorogenic sediment distribution are all a function of the geometry, kinematics, and rate of deformation in a fold‐thrust‐belt‐foreland basin (FTB‐FB) system. To determine the timing and rate of deformation in the northern Bolivian Andes, we link thermokinematic modeling to a sequentially forward modeled, balanced cross section isostatically accounting for thrust loads and erosion. Displacement vectors, in 10 km increments, are assigned variable ages to create velocity fields in a thermokinematic model for predicting thermochronometer ages. We match both the pattern of predicted cooling ages with the across strike pattern of measured zircon fission track, apatite fission track, and apatite (U‐Th)/He cooling ages as well as the modeled age of FB formations to published sedimentary sections. Results indicate that northern Bolivian FTB deformation started at 50 Ma and may have begun as early as 55 Ma. Acceptable rates of shortening permit either a constant rate of shortening (~4–5 mm/yr) or varying shortening rates with faster rates (7–10 mm/yr) at 45–50 Ma and 12–8 Ma, significantly slower rates (2–4 mm/yr) from 35 to 15 Ma and indicate the northern Bolivian Subandes started deforming between 19 and 14 Ma.

Large-scale patterns of turnover and Basal area change in Andean forests.

General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century.

Climate controls on Andean precipitation δ18O interannual variability

The stable oxygen isotopic composition of precipitation (δ18Op) is used as a proxy for modern and past atmospheric, biologic, and surface processes. Although the physical processes that fractionate 18O in vapor are known, regional controls of δ18Op are not well understood. Here we present results from a limited‐domain general circulation model (REMOiso) to quantify regional controls on modern (1976–1999) interannual and spatial variations of δ18Op across four Andean domains spanning 50° latitude. Results are compared to observed δ18Op from meteorological stations. Simulated annual amount‐weighted mean δ18Op ranges between −4 and −7‰ (0–5°S), −8 and −20‰ (14°S–26°S), −4 and −8.5‰ (30°S–35°S), and −7 to −10‰ (45°S–50°S). Relationships between climate and δ18Op on interannual timescale vary along the Andes and are tied to changes in precipitation and large‐scale dynamics. In the northern Andes, interannual variations in δ18Op are mainly associated with precipitation amounts driven by low‐latitude sea surface temperature and Amazon Basin conditions. In the north central Andes, δ18Op correlates with precipitation amount and wind trajectory, which is related to the position of the Bolivian High. In the south central Andes, δ18Op variability is mainly influenced by precipitation amounts that are controlled by the position and strength of the westerlies. In the southern Andes, interannual δ18Op variability is linked to the intensification and weakening of the South Pacific High. The regional climate‐δ18Op relationships are discussed in the context of pre‐Quaternary sedimentary δ18O proxy records.

Agricultural Intensification, Market Participation, and Household Demography in the Peruvian Andes

The causes of agricultural intensification in a peasant community in the north central Andes are explored using a methodology derived from the tradition of Systems Ecology. Hypotheses derived from different research traditions—mainly development economics and anthropology—regarding the causes of intensification are integrated and evaluated for their relative effects. It is found that among the variables, household size is better at explaining the degree of intensity with which labor and technology are employed. The results suggest that technologically-driven agricultural intensification is generally forced upon households by the diminishing returns of their labor, and that this process is normally accompanied by increased financial debt for those peasant households who remain in agriculture and do not completely migrate to regional urban centers.

Engineered highlands: the social organization of water in the ancient north-central Andes (AD 1000–1480)

Recent research in the Late Intermediate Period (ad 1000–1480) north-central Andes has emphasized the segmentary and egalitarian nature of late prehispanic Huaylas communities in the region. This form of devolved power nevertheless conceals investiture of authority in a person or group, albeit temporarily. Given the ubiquitous importance of water in the Andes, I suggest that this type of power could well have rested on special ‘managers’ closely involved in the organization of water and its concomitant hydrological infrastructure, working for the wider community and its leaders. Centring on archaeological evidence from the Cordillera Negra in the Ancash highlands the area demonstrates the development of a complex suite of hydraulic technology. It is this unique setting, including previously sparsely recorded structures such as silt dams and silt reservoirs, which provides the technological suite necessary to test these preliminary ideas. The approach taken here is an attempt to revisit some of Karl Wittfogel's concepts, adapting them to include a community-based bottom-up perspective to the ‘hydraulic hypothesis’.

U-Pb geochronologic evidence for the evolution of the Gondwanan margin of the north-central Andes

We investigated the Neoproterozoic–early Paleozoic evolution of the Gondwanan margin of the north-central Andes by employing U-Pb zircon geochronology in the Eastern Cordilleras of Peru and Ecuador using a combination of laser-ablation–inductively coupled plasma–mass spectrometry detrital zircon analysis and dating of syn- and post-tectonic intrusive rocks by thermal ionization mass spectrometry and ion microprobe. The majority of detrital zircon samples exhibits prominent peaks in the ranges 0.45–0.65 Ga and 0.9–1.3 Ga, with minimal older detritus from the Amazonian craton. These data imply that the Famatinian-Pampean and Grenville (= Sunsas) orogenies were available to supply detritus to the Paleozoic sequences of the north-central Andes, and these orogenic belts are interpreted to be either buried underneath the present-day Andean chain or adjacent foreland sediments. There is evidence of a subduction-related magmatic belt (474–442 Ma) in the Eastern Cordillera of Peru and regional orogenic events that pre- and postdate this phase of magmatism. These are confirmed by ion-microprobe dating of zircon overgrowths from amphibolite-facies schists, which reveals metamorphic events at ca. 478 and ca. 312 Ma and refutes the previously assumed Neoproterozoic age for orogeny in the Peruvian Eastern Cordillera. The presence of an Ordovician magmatic and metamorphic belt in the north-central Andes demonstrates that Famatinian metamorphism and subduction-related magmatism were continuous from Patagonia through northern Argentina to Venezuela. The evolution of this extremely long Ordovician active margin on western Gondwana is very similar to the Taconic orogenic cycle of the eastern margin of Laurentia, and our findings support models that show these two active margins facing each other during the Ordovician.

The biogeography of the austral, subalpine genus Ourisia (Plantaginaceae) based on molecular phylogenetic evidence: South American origin and dispersal to New Zealand and Tasmania

Molecular phylogenetic analyses of 26 of the 28 species of Ourisia, including eight of ten subspecies and two purported natural hybrids, are presented and used to examine the biogeography of the genus, which is distributed in subalpine to alpine habitats of South America, New Zealand and Tasmania. Gondwanan vicariance, often cited as the cause of this classic austral biogeographical pattern, was rejected by parametric bootstrapping of our combined dataset. Alternatively, various lines of evidence are presented in favour of a South American origin of Ourisia and subsequent dispersal to Australasia. Specifically, the genus likely arose in the Andes of central Chile and spread to southern Chile and Argentina, to the north-central Andes, and finally to Tasmania and New Zealand. The ancestor of the New Zealand species probably first arrived on the South Island, where the New Zealand species of Ourisia are most diverse, and migrated to the North and Stewart Islands. Because the Tasmanian and New Zealand species are sister to one another, the direction of dispersal between these two areas is equivocal. These results agree with other molecular phylogenetic studies that show that past dispersal between southern hemisphere continents has played an important role in the evolutionary history of many high-elevation austral plants. Our data also show that within South America, many of the geographical barriers (with the exception of the Atacama Desert) that have played a role in the evolution of other plant groups have not affected Ourisia species. Within New Zealand, the phylogeny and biogeography of species of Ourisia coincide with the geological history of the country and patterns of other alpine plants. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 479–513.

The Evolution of Authority and Power at Chavin de Huantar, Peru

The Early Horizon type site of Chavin de Huantar, located in the north-central Andes of modern Peru, is distinguished by a long sequence of construction, as well as outstanding features such as abundant lithic art, use of cut stone in construction, a complex of underground gallery systems, and exceptional alteration of local land forms. This chapter explores the implications of these characteristics for the evolution of power and authority at this site across the later Initial Period and Early Horizon (approximately 1300 to 600 B.C.). Particular attention is focused on the concepts of power and authority in relation to religious belief systems and the intrinsic factors that might have connected the site's characteristics to a developing system for convincing populations to increasingly accept the dominance of a priestly leadership. These characteristics argue that not only were the emerging authorities at Chavin exceptionally creative in their manipulation of the human mind through landscape, architecture, images, sound, light, and the use of psychoactive drugs but also that this apparent highly planned ritual context demonstrates the very intentional and conscious strategies employed in the transformation of early politico-religious organization.

Regional crustal thickness and precipitation in young mountain chains.

Crustal thickness is related to climate through precipitation-induced erosion. Along the Andes, the highest mountains and thickest crust (approximately 70 km) occur at 25 degrees south, a region of low precipitation. Westerly winds warm passing over the Atacama Desert; precipitation is modest in the High Andes and eastward over the Altiplano. Severe aridity, hence low erosion rates, helps to account for the elevated volcanogenic contractional arc and high, internally draining plateau in its rain shadow. Weak erosion along the north-central arc provides scant amounts of sediment to the Chile-Peru Trench, starving the subduction channel. Subcrustal removal might be expected to reduce the crustal thickness, but is not a factor at 25 degrees south. The thickness of the gravitationally compensated continental crust cannot reflect underplating and/or partial fusion of sediments, but must be caused chiefly by volcanism-plutonism and contraction. Contrasting climate typifies the terrain at 45 degrees south where moisture-laden westerly winds encounter a cool margin, bringing abundant precipitation. The alpine landscape is of lower average elevation compared with the north-central Andes and is supported by thinner continental crust (approximately 35 km). Intense erosion supplies voluminous clastic debris to the offshore trench, and vast quantities are subducted. However, the southern Andean crust is only about half as thick as that at 25 degrees south, suggesting that erosion, not subcrustal sediment accretion or anatexis, is partly responsible for the thickness of the mountain belt. The Himalayas plus Tibetan Plateau, the Sierra Nevada plus Colorado Plateau, and the Japanese Islands exhibit analogous relationships between crustal thickness and climate.