Glaciomarine sediments and facies associations, southern York County, Maine

Geology of the coastal lowlands, Boston to Kennebunk, Maine: The 76th annual meeting New England Intercollegiate Geological Conference, Danvers, Massachusetts, October 12-14, 1984: Trip A-

Anisotropic focusing characteristics of micro-domain structures within crystalline Sr_0.61Ba_0.39Nb₂O₆ : the crystal ball

We report the anisotropic focusing characteristics of a spherically configured region of micro-domains that have been induced within a cubic shaped crystal of Ce:doped Sr0.61Ba0.39Nb2O6. The internal spherical structure focuses extraordinary polarised light, but not ordinary polarised. The spherical region, which is easily observed via scattering, is formed as the crystal cools down, after a repoling cycle through the Curie temperature, with an applied field. Analytic modelling of the thermal gradients that exist within the crystal during cooling reveals a small (< 1°) temperature difference between the central and outside regions. The similarity in shape between these temperature profiles and the observed scattering region suggests a possible mechanism for the growth of this spherical micro-domained structure

Recent sedimentological onterpretations in the Avalon terrane of the Boston Basin, Massachusetts

The depositional history of the Boston Basin remains somewhat enigmatic and controversial despite nearly over a century of research. Resolution of the basin's geologic history has remained formidable and complex due. In part, to attempts to work within the existing stratigraphy which often carried with it historic interpretations, many of which went uncontested. More importantly however, our knowledge of depositional systems and mechanisms has Increased significantly over this span of time. Reinterpretatlons In light of these advances were not only Inevitable but neccessary. As a consequence of the circumstances described above, our reinvestigation into the depositional history of the Boston Basin succession, principally the Boston Bay Group, has centered on recognizing, measuring, and coding a suite of facies whose textures In many Instances can be closely linked to specific depositional mechanisms responsible for the emplacement of the facies in question. From this facies analysis a preliminary depositional model for the Boston Basin has begun to emerge. It appears that the Boston Basin originated as a rifted successor, or arc-related basin either just prior to the closure of the Cadomlan Ocean or during the opening of Iapetus. The early history of the basin Is marked by the presence of a suite of bimodal volcanics In the form of water-lain tuffs, dikes, sills, and flows, and coarse debris flows. Geochemlcal markers suggest that the basin was In contact with the open ocean very early In its history. The next stage In the evolution of the Boston Basin was marked by the development of a rapidly prograding submarine elope/fan succession. The slope/fan Betting appears to have been characterized by the deposition of ice frontal and/or ice-rafted dlamictons which periodically overloaded the slope Initiating sediment gravity flows which reworked and redistributed sediment downslope. During periods of more equable climate and/or tectonic quiescence, blankets of fine sand and mud were deposited. There Is no evidence of a shelf or shelf-type deposits during this time. The last stage in the evolution of the basin was the appearance of shelf sediments such as quartz and calcareous sands, and muds with abundant organic matter and shelled organisms. There Is also evidence for climatic warming which is suggested to have been brought about by a tectonlcally-forced rise In eustatic sea-level. RÉSUMÉ L'hlstoire sédlmentalre du Bassln de Boston Bouleve encore quelques enigmes et controversy et, cela, après près d'un slecle de travaux. Dans une certain mesure, la résolution de l'histoire géologlque du bassln est demeurée formidable et complexe par suite des tentatlves de travalller au sein de la stratigraphie actuelle qui. elle, comportalt souvent des interprètations hlstoriques rareaent mises en doute. Or, plus important est le bond en avant saislssant qu'à fait notre connalssance des systèmes et mecanlsmes de dépôt durant cette période. Il devint done non seuleoent inevitable. mala bien nécessaire de réconsiderér lea conceptions traditionnelles a la lumière de ces acquis. Pour ce falre, notre reexamen de l'hlstoire sédimentalre de la succession du Bassln de Boston, et surtout du Groupe de Boston Bay, s'est axe sur la reconnaissance, la mesure et le codage d'une suite de faciès dont les textures sont souvent reliées de façon intime aux mecanismes de dépôt distincts responsables de la raise en place désdits faciès. Cette analyse faclologique commence à éngendrer un modèle préliminaire du dépôt dans le Bassln de Boston. Il semble que le Bassin de Boston alt débuté sous forme d'un rift successeur ou d'un bassln allié à un arc solt juste avant le serrage de l’Océan Cadomien, solt lors de l’ouverture de L'Iapetus. L'hlstoire du bassin est d'abord marquée par la présence d'une suite de volcanites blmodales sous formes de tufa aquatiques, dykes, filons-couches. coulées et coulées de débris. Les marqueurs géochimiques suggérent que le bassin était ouvert sur le large des l’amorce de son hlstoire. Le stade suivant dans l’évolution du Bassln de Boston fut marque par le développement d'une séquence de pente et cone sous-marlns à progradation rapide. L'environnement de pente et cone semble avoir été carsctérise par le dépôt de diamictons glaciaires frontaux et/ou supraglaciares qui ont surcharge périodiquetoent la pente, declencbant alnsi des écoulements gravitalres qui ont repris les sédiments et les ont redistribue en bas de pente. Les périodes de climat plus uniforme et/ou de stase tectonique donnerent lieu à des épandages de sable fin et de boue. On ne trouvé pas trace d'une plate-forme ou de dépôts typiques d'une plate-forme lors de cette période. La derniere phase évolutive du bassin correspond à L’apparltlon de sédiments de plate-forme tels que des sables quartzeux et calcaires alnsi que des boues riches en raatiere organique et en organlsmes coquilllers. Certains Indices temoignent d'un rechauffement climatlque que l'on croit du a une élevation eustatlque du niveau marin en reponse aux sollicitations de la tectonique. [Traduit par le journal

EFFECT OF RECREATIONAL TRAIL TRAFFIC LEVEL ON EASTERN RED-BACKED SALAMANDER (PLETHODON CINEREUS) RELATIVE ABUNDANCE

The effects of roads and trails on terrestrial salamanders, primarily plethodontids, can be important. The abundance of terrestrial salamanders often increases with distance from roads. Less is known about the effects of recreational or hiking trails on terrestrial salamanders than is known about the effects of roads. We explored how low and high traffic trails in a suburban biological reserve affect the relative abundance of Eastern Red-backed Salamanders (Plethodon cinereus). We found more salamanders under cover objects next to low traffic trails compared to either high traffic trails or wooded areas without trails. At wooded sites, we found only striped morphs whereas at high traffic sites we found only unstriped morphs. Low traffic sites included a range of color morph frequencies. The proportion of females found in each site did not differ, nor did the mean size of the salamanders. Our results suggest that the impact of recreational walking trails needs to be examined more closely to see how and why the distributions of P. cinereus, and potentially other woodland salamanders, are affected and what trail characteristics are important in driving the apparent effects. Such information will contribute to the design and maintenance of walking trails in natural areas that minimize effects on terrestrial salamanders, and likely other organisms

Reconnaissance surficial geology of the Waterville [15-minute] quadrangle, Maine

Maine Geological Survey, Open-File Map 86-51https://digitalmaine.com/mgs_maps/1720/thumbnail.jp

Reconnaissance surficial geology of the Burnham [15-minute] quadrangle, Maine

Maine Geological Survey, Open-File Map 86-3https://digitalmaine.com/mgs_maps/1719/thumbnail.jp

End Moraines and Glaciofluvial Deposits, Cumberland and York Counties, Maine

Maine Geological Survey. Black and white wall map showing end moraines, eskers and crevasse fillings, and glaciofluvial depositshttps://digitalmaine.com/mgs_maps/2180/thumbnail.jp

Reconnaissance surficial geology of the Vinalhaven [15-minute] quadrangle, Maine

Maine Geological Survey, Open-File Map 86-52https://digitalmaine.com/mgs_maps/1722/thumbnail.jp