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This month's column is Part 2 of a contribution from my daughter Glenna, who recently completed her PhD studies in Environmental Science from the University of Copenhagen in Denmark. Her article explores the current landscape of global critical raw materials (CRM) trends in research and the applications of atomic spectroscopy (AS), including inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-optical emission spectrometry (ICP-OES), and X-ray analytical techniques in their identification of diverse industrial and environmental media, which have been essential in method validation and quantification of CRMs in complex matrices presenting high risks of interference. Some important examples to be presented include rare earth elements (REEs) in water leaching purification (WLP) residues that co-occur with radioactive materials; REEs and other metals in acid mine drainage (AMD) environments; REEs in coal combustion (fly ash) residues; arsenic (As) from groundwater treatment sediment; and platinum-group elements (PGEs) from sewage sludge. The article also classifies the different techniques in use at each stage of the CRM recovery train, investigates present challenges to each analytical method, and discusses the problem-solving tools used., - Rob Thomas, Column Editor Part 1 of this article focused on the overview of critical raw materials (CRMs), the global context for sustainable sourcing of CRMs, and the recent […]

Many shorcbirds rely on sandy beaches to breed. However, these ecosystems arc rare and unstable on the Guianas coast because of sediment dynamics. Nonetheless, they host 2 shorcbirds that breed in the Nearctic and the Neotropic: Wilson's Plover (Charadrius wilsonia) and Black-necked Stilt (Himantopus mexicanus). We studied their breeding biology in the Amana Nature Reserve, a Ramsar Site in French Guiana, on sandy beaches bordered by brackish lagoons during 1 breeding season. From early June to late August 2008, we located and monitored 19 Wilson's Plover and 15 Black-necked Stilt nests. Most nests were associated with bare ground. While stilts preferred to build their nests with twigs closer to lagoons, plovers did not show any preference in nest location and composition. For plovers and stilts, clutch sizes were 2-3 eggs or 3-4 eggs per nest, respectively, and the mean egg volumes were 12.1 [+ or -] 0.4 c[m.sup.3]and 20.6 [+ or -] 0.6 c[m.sup.3], respectively. The apparent hatching success for both species was low, 11% for Wilson's Plover and 13% for Black-necked Stilt, whereas daily nest survival was high for both species. Clutch sizes, egg dimensions, and egg colorations were comparable to those described elsewhere, but the breeding season started later than at other localities for the Wilson's Plover. In French Guiana, the apparent nest success values for both species were much lower than those reported in the United States and the West Indies but seemed slightly higher than in Brazil. Human activity impacts were limited in our study area and did not explain the low nest success values found. Beach flooding at high tide was the main cause of clutch failure, followed by predation. Ironically, flooding allows the maintenance of this low, open, and debris-covered habitat used by beach-nesting shorebirds. Received 28 September 2022. Accepted 11 August 2023. Key words: breeding success, French Guiana, nest survival, sandy beaches, shorebird ecology. Beaucoup de limicoles dependent des plages sableuses pour se reproduire. En raison de la dynamique sedimentaire, ces plages sont rares et instables sur la cote des Guyanes. Neanmoins, elles abritent deux especes de limicoles nichant dans le nearctique et le neotropique: le Pluvier de Wilson (Charadrius wilsonia) et l'Echasse d'Amerique (Himantopus mexicanus). Nous avons etudie la biologie de leur reproduction dans la reserve naturelle de I'Amana, un site Ramsar en Guyane Francaise, sur des plages sableuses bordees de lagunes saumatres pendant une saison de reproduction. De debut juin a fin aout 2008, nous avons localise et suivi 19 nids de Pluvier de Wilson et 15 nids d'Echasse d'Amerique. La plupart des nids etaient associes a des sois nus. Le pluvier de Wilson n'a montre aucune preference quant a l'emplacement et a la composition des nids. Tandis que l'Echasse d'Amerique preferait construire son nid avec des brindilles plus pres des lagunes. La taille des couvees etait respectivement de 2-3 ceufs et de 3--4 ceufs par nid, et le volume moyen des oeufs etait de 12.1 [+ or -] 0.4 c[m.sup.3] et 20.6 [+ or -] 0.6 c[m.sup.3]. Le succes apparent d'eclosion etait faible pour les 2 especes, avec 11% pour le pluvier et 13% pour l'echasse, alors que la survie joumaliere des nids etait haute. La taille des pontes, la dimension et la coloration des ceufs etaient comparables a celles decrites ailleurs, mais la periode de reproduction etait plus tardive chez le Pluvier de Wilson. En Guyane francaise, les succes apparents des nids des deux especes etaient beaucoup plus faibles que ceux observes aux Etats-Unis et aux Antilles, mais ils semblaient legerement plus eleves qu'au Bresil. Les activites humaines etaient limitees sur le site d'etude et n'ont pas explique ce faible succes. La submersion des plages lors des grandes marees etait la principale cause de l'echec des pontes, suivie par la predation. Mais ces submersions ont paradoxalement participees au maintien de cet habitat bas, ouvert et couvert de debris utilise par les limicoles nichant sur les plages. Mots cles: ecologie des limicoles, Guyane francaise, plages de sable, succes reproducteur, survie des nids., The 1,600 km-long Guianas coast, located between the Amazon Delta in Brazil and the Orinoco Delta in Venezuela, has an Amazon-influenced, constantly evolving shoreline composed of shifting muddy banks and [...]

The Ganderian Cambrian-Ordovician Miramichi terrane narrows in east-central Maine and terminates at the junction of faults that separate it from the mostly Silurian Central Maine/Aroostook-Matapedia basin (CMAM) to thenorthwest and Fredericton trough to the southeast. The terrane was emergent after Middle Ordovician recumbent folding and shed sediment to both adjacent depocenters. Its boundary faults are the youngest deformation events and play important roles in its termination, but do not by themselves explain it. The presence of distinctive CMAM strata southeast of the northwest boundary fault indicates that the first step in developing the current relationships was an episode of hitherto unrecognized late Silurian eastward thrusting. In the northern (Danforth) segment of the terrane, intermediate facies CMAM strata were thrust onto their Miramichi source rocks. The thrust sheet was deformed by Acadian upright folds, then dissected by dip-slip offset along boundary and internal faults prior to intrusion of the 409 [+ or -] 2 Ma Skiff Lake pluton. Subsequent erosion isolated a remnant of the thrust sheet as the Dill Hill klippe, its allochthonous CMAM strata isolated among Miramichi rocks. The southern (Greenfield) segment experienced similar events, but current relationships are different and timing of the late-stage faults is not well constrained. Allochthonous CMAM strata may have overridden the Miramichi terrane completely, so that a remnant of distinctive CMAM strata is now exposed east of the Miramichi terrane in fault contact with rocks of the Fredericton trough. The entire Greenfield segment is interpreted as a fault block exposed within the thrust sheet. Le terrane cambro-ordovicien gand rien de Miramichi se r tr cit dans le centre-est du Maine, et il prend fin la jonction des failles qui le s pare du bassin principalement silurien du centre du Maine/Aroostook-Matap dia (CMAM) au nord-ouest et de la cuvette de Fredericton au sud-est. Le terrane a merg apr s la formation de plis couch s de l'Ordovicien moyen et la diffusion de s diments dans deux zones de d p t adjacentes. Ses failles limitrophes constituent les pisodes de d formation les plus r cents, et ils jouent des r les importants dans sa terminaison, sans toutefois expliquer celle-ci par eux-m mes. La pr sence de strates distinctives du bassin CMAM au sud-est de la faille limitrophe nord-ouest r v le que le premier stade de l'apparition des liens existants a t un pisode de chevauchement vers l'est du Silurien tardif qui n'avait pas t reconnu jusqu'ici. Dans le segment septentrional (Danforth) du terrane, des strates du faci s interm diaire du bassin CMAM ont t charri es sur leurs roches m res de Miramichi. La nappe de charriage a t d form e par des plis droits acadiens, puis diss qu e par un d placement horizontal de rejet-pendage le long des failles limitrophes et internes avant l'intrusion du pluton de 409 [+ or -] 2 Ma du lac Skiff. Une rosion subs quente a isol un vestige de la nappe de charriage pour cr er la klippe de la colline Dill, ses strates allochtones du bassin CMAM isol es parmi les roches de Miramichi. Le segment m ridional (Greenfield) a t touch par des ph nom nes similaires, mais ses liens actuels sont diff rents et le moment de la formation des failles tardives n'est pas bien d limit . Les strates allochtones du bassin CMAM pourraient avoir compl tement recouvert le terrane de Miramichi, de sorte qu'un vestige des strates distinctives du bassin affleure aujourd'hui l'est du terrane de Miramichi en contact faill avec les roches de la cuvette de Fredericton. L'ensemble du segment de Greenfield est interpr t comme un bloc faille d couvert l'int rieur de la nappe de charriage., INTRODUCTION Maine and New Brunswick are underlain by several northeast-trending terranes of late Cambrian to Middle Ordovician strata isolated within extensive areas of Upper Ordovician to Middle Devonian cover rocks [...]

The notion of late-Cenozoic uplift was implied in 1865 by Whitney, who assumed a buried bedrock canyon lay beneath the Table Mountain latite flow and above the modern Stanislaus River canyon, with the difference between the two longitudinal profiles suggesting post-latite uplift. However, only a series of buried bedrock ridges exists and no uplift is inferred. I briefly present thirty-three key sites of about three hundred remnants in the entire Sierra Nevada, from north of the Feather River south to the Kern River. These include Late Cretaceous strata, Eocene strata, Oligocene rhyolites, Mio-Pliocene andesites, and Quaternary basalts, some remnants on canyon floors but most on lower slopes, preserving topography at the time of deposition. I found no evidence of late-Cenozoic incision, which is required under the late-Cenozoic uplift paradigm. Instead, each site contains verifiable field evidence that challenges the uplift paradigm. Moreover, the results are consistent with the range having a common uplift history: the crest elevation, drainage topography, and relief developed in the Late Cretaceous, and only minor changes occurred in post-Eocene time. This supports uplift studies in the northern Sierra based on hydrogen and oxygen isotopes on auriferous deposits, and supports pediment ages of 40+ Ma in the southern Sierra. Uplift studies based on thermochronology and numerical modeling, on cave-sediment dating and its implied incision, and on significant denudation on benchlands cannot be reconciled with verifiable field evidence. Finally, migration of giant sequoias southwest into the Sierra Nevada was possible only from late in the Cretaceous, when the Nevadaplano came into existence and the range was high, negating any Sierran late-Cenozoic uplift paradigm. Keywords: Sierra Nevada, Sierra Nevada uplift, Sierra Nevada geomorphology, Late Cretaceous Sierra Nevada, Age of Sierra Nevada canyons., Introduction This manuscript covers fieldwork that I, usually with William A. 'Bill' Peppin, have conducted since 2013. Back in late October of that year we made our last field trip, [...]