Fisheries and Oceans Canada (DFO) Maritime Science Branch has collected grain size data from sediment and water column samples using bottle samples, sediment cores, and sediment grabs as part of numerous research projects not only in the Atlantic provinces, but also worldwide. The data collected by DFO focuses on the fine grained (<1mm) particles as these are both a source of food and means of contaminant transport. Grain size data are used to study the fate and distribution of complimentary chemistries like heavy metals, pesticides, hydrocarbons, aquaculture waste as well as a variety of physical processes such as the resuspension and transport of sediment.

This record contains results from chemical analysis including suspended nitrogen (mg/g), suspended carbon (mg/g), and phosphorus (mg/g) based on dry weight sediment samples collected in the Beaufort Sea.

Grain size is the most fundamental physical property of sediment, and these data are widely used in a variety of applications in science. Marine expeditions of the Geological Survey of Canada have been collecting grain size information on seabed and sub-seabed samples for over 50 years. Results have been recorded at 5th phi midpoints since the early 1990's in contrast to the earlier full, half or quarter phi interval end point values. Users of high resolution data must note that the sum of %Silt and %Clay equals the total %Mud makeup and that %Gravel, %Sand, %Silt and %Clay sum to 100%. Summary statistics include percentages of gravel, sand, silt, clay and mud as well as mean, kurtosis, skewness and standard deviation. The quality of these data varies. Results should be used with some caution as they may not be fully representative of seabed grainsize, particularly in areas of sandy and coarser sediment (e.g., sand and mud can leak out of the sampler during recovery). Canada makes no representation or warranty of any kind with respect to the accuracy, usefulness, novelty, validity, scope, completeness or currency of the data and expressly disclaims any implied warranty of merchantability or fitness for a particular purpose of the data. For the purpose of the web mapping service, grain size data are sorted by the expedition id. Coarse and detailed grain size distribution plots are shown when a point is chosen. If the sample contains more that one sub-sample ( e.g., as with a piston core sequence), the grain size plots are stacked in the display window from the top of the core downwards.

Monitoring activities have collected bulk suspended sediment samples using continuous flow centrifuges and Phillips Tube samplers in the Lower Athabasca River and tributaries respectively. Further, in the absence of pre-development monitoring for this region, high fidelity dated lake sediment cores were used to assess the natural range in contaminant deposition to this region and to obtain a historical perspective of contaminant loadings. All sediments (suspended river and lake cores) have been analyzed in the laboratory for sediment quality variables as per Appendix B in the Integrated Monitoring Plan (cores were also analyzed for paleo indicators of ecosystem health such as diatoms). In addition, as the Lower Athabasca river bed sediments are known to shift and migrate downstream, bathymetric maps of the bed-channel morphology over time was also completed. This will allow for estimates of bed sediment transport downstream for the period of survey, and be useful in calibration/validation of sediment and contaminant numerical transport models.

Regional stream sediment geochemical data compilationNovember 2020Release notesThe regional stream sediment geochemical data compilation comprises data for more than 30 000 samples across Yukon. This compilation updates the work of Héon (2003). This new compilation includes results from the reanalysis of more than 24 000 samples; inductively coupled plasma mass spectrometry (ICPMS) analysis provides upgraded detection limits and a broader range of elements relative to previous analytical data. In addition to analytical data, efforts have been made to improve sample location accuracy. The data in this release are organized by analytical method with the geodatabase having six feature classes:1. RGS_SITE_WATER - site specific physiography and water quality data. These data are unchanged from the original releases. 2. RGS_HEON - the same data as released in Héon (2003) with minor updates to sample location. 3. RGS_AAS - all samples analyzed by atomic absorption spectrometry. Most of these data are superseded by INAA and ICPMS data. 4. RGS_INAA - all samples analyzed by instrumental neutron activation analysis (INAA) and fire assay-neutron activation (FA-NA) analysis. 5. RGS_ICPMS - all samples analyzed by inductively coupled plasma mass spectrometry (ICPMS). 6. RGS_All - includes all AAS, INAA and ICPMS data. Collection of stream sediment samples in Yukon began in 1976 and ended in 2006. Three analytical methods have been used to analyze the minus 0.177 mm fraction (-80 mesh) of these samples: AAS, INNA (and FA-NA) and ICPMS. A simple description of each method is given below.For atomic absorption spectrometry (AAS) a 1 g aliquot is 'partially digested' using Lefort aqua regia or concentrated hot nitric acid. The digestion product is analyzed using an atomic absorption spectrometer. Oxide and silicate minerals are partially digested while some sulphide minerals are erratically volatilized. This means that AAS cannot be used to obtain accurate REE, Ta, Nb, As, Sb, Sn, Hg, Cr, or Au determinations.For instrumental neutron activation analysis ( INAA), aliquots of sieved sediment (the minus 0.177 mm fraction) or milled rock ranging from 5 to 40 g are encapsulated and irradiated in a nuclear reactor before counting the primary gamma radiation induced by the neutron irradiation with a high resolution germanium gamma ray detector. Fire assay-neutron activation (FA-NA) analysis is similar but includes a pre-concentration fire assay step prior to irradiation and analysis. Results for both INAA and FA-NA are similar to those for samples analyses by fusion or other total digestion techniques. Neutron activation detection limits are typically higher than those by acid digestion - ICPMS. Commodity and pathfinder elements such as Au, As, Sb and W have reasonable detection limits by INAA and the data generated are relatively precise.For ICPMS analysis, aliquots of sieved sediment ( the minus 0.177 mm fraction) ranging from 0.5 to 1 g are prepared using a partial digestion technique, typically aqua regia, followed by analysis of dissolution product by ICPMS. Sulphide minerals are completely oxidized and dissolved whereas most oxide and silicate minerals are only partially digested. This means that results produced by partial digestion methods are acceptable for elements such as Ag, As, Mo, Ni, Pb, Sb, Tl, and Zn but values for elements such as Al, Ba, Cr, Fe, P, Sn, Ti, Y, and Zr are likely to not reflect the actual element concentration in a sample. The sample size used for routine RGS sample analysis is too small be representative of Au in the original sample and thus Au by aqua regia digestion - ICPMS has poor precision.Further upgrades to this database are not anticipated. All samples that could be found in the GSC-Ottawa warehouse have been reanalyzed using ICPMS. Any errors or omissions in this database should be reported to the Yukon Geological Survey. Your feedback contributes to improving the accuracy of the geoscience databases for Yukon.Contact: [YGSMinerals@yukon.ca](mailto:YGSMinerals@yukon.ca) ; [geology@yukon.ca](mailto:geology@yukon.ca)Distributed from [GeoYukon](https://yukon.ca/geoyukon) by the [Government of Yukon](https://yukon.ca/maps) . Discover more digital map data and interactive maps from Yukon's digital map data collection.For more information: [geomatics.help@yukon.ca](mailto:geomatics.help@yukon.ca)

Regional stream sediment geochemical data compilationNovember 2020Release notesThe regional stream sediment geochemical data compilation comprises data for more than 30 000 samples across Yukon. This compilation updates the work of Héon (2003). This new compilation includes results from the reanalysis of more than 24 000 samples; inductively coupled plasma mass spectrometry (ICPMS) analysis provides upgraded detection limits and a broader range of elements relative to previous analytical data. In addition to analytical data, efforts have been made to improve sample location accuracy. The data in this release are organized by analytical method with the geodatabase having six feature classes:1. RGS_SITE_WATER - site specific physiography and water quality data. These data are unchanged from the original releases. 2. RGS_HEON - the same data as released in Héon (2003) with minor updates to sample location. 3. RGS_AAS - all samples analyzed by atomic absorption spectrometry. Most of these data are superseded by INAA and ICPMS data. 4. RGS_INAA - all samples analyzed by instrumental neutron activation analysis (INAA) and fire assay-neutron activation (FA-NA) analysis. 5. RGS_ICPMS - all samples analyzed by inductively coupled plasma mass spectrometry (ICPMS). 6. RGS_All - includes all AAS, INAA and ICPMS data. Collection of stream sediment samples in Yukon began in 1976 and ended in 2006. Three analytical methods have been used to analyze the minus 0.177 mm fraction (-80 mesh) of these samples: AAS, INNA (and FA-NA) and ICPMS. A simple description of each method is given below.For atomic absorption spectrometry (AAS) a 1 g aliquot is 'partially digested' using Lefort aqua regia or concentrated hot nitric acid. The digestion product is analyzed using an atomic absorption spectrometer. Oxide and silicate minerals are partially digested while some sulphide minerals are erratically volatilized. This means that AAS cannot be used to obtain accurate REE, Ta, Nb, As, Sb, Sn, Hg, Cr, or Au determinations.For instrumental neutron activation analysis ( INAA), aliquots of sieved sediment (the minus 0.177 mm fraction) or milled rock ranging from 5 to 40 g are encapsulated and irradiated in a nuclear reactor before counting the primary gamma radiation induced by the neutron irradiation with a high resolution germanium gamma ray detector. Fire assay-neutron activation (FA-NA) analysis is similar but includes a pre-concentration fire assay step prior to irradiation and analysis. Results for both INAA and FA-NA are similar to those for samples analyses by fusion or other total digestion techniques. Neutron activation detection limits are typically higher than those by acid digestion - ICPMS. Commodity and pathfinder elements such as Au, As, Sb and W have reasonable detection limits by INAA and the data generated are relatively precise.For ICPMS analysis, aliquots of sieved sediment ( the minus 0.177 mm fraction) ranging from 0.5 to 1 g are prepared using a partial digestion technique, typically aqua regia, followed by analysis of dissolution product by ICPMS. Sulphide minerals are completely oxidized and dissolved whereas most oxide and silicate minerals are only partially digested. This means that results produced by partial digestion methods are acceptable for elements such as Ag, As, Mo, Ni, Pb, Sb, Tl, and Zn but values for elements such as Al, Ba, Cr, Fe, P, Sn, Ti, Y, and Zr are likely to not reflect the actual element concentration in a sample. The sample size used for routine RGS sample analysis is too small be representative of Au in the original sample and thus Au by aqua regia digestion - ICPMS has poor precision.Further upgrades to this database are not anticipated. All samples that could be found in the GSC-Ottawa warehouse have been reanalyzed using ICPMS. Any errors or omissions in this database should be reported to the Yukon Geological Survey. Your feedback contributes to improving the accuracy of the geoscience databases for Yukon.Contact: [YGSMinerals@yukon.ca](mailto:YGSMinerals@yukon.ca) ; [geology@yukon.ca](mailto:geology@yukon.ca)Distributed from [GeoYukon](https://yukon.ca/geoyukon) by the [Government of Yukon](https://yukon.ca/maps) . Discover more digital map data and interactive maps from Yukon's digital map data collection.For more information: [geomatics.help@yukon.ca](mailto:geomatics.help@yukon.ca)

Regional stream sediment geochemical data compilationNovember 2020Release notesThe regional stream sediment geochemical data compilation comprises data for more than 30 000 samples across Yukon. This compilation updates the work of Héon (2003). This new compilation includes results from the reanalysis of more than 24 000 samples; inductively coupled plasma mass spectrometry (ICPMS) analysis provides upgraded detection limits and a broader range of elements relative to previous analytical data. In addition to analytical data, efforts have been made to improve sample location accuracy. The data in this release are organized by analytical method with the geodatabase having six feature classes:1. RGS_SITE_WATER - site specific physiography and water quality data. These data are unchanged from the original releases. 2. RGS_HEON - the same data as released in Héon (2003) with minor updates to sample location. 3. RGS_AAS - all samples analyzed by atomic absorption spectrometry. Most of these data are superseded by INAA and ICPMS data. 4. RGS_INAA - all samples analyzed by instrumental neutron activation analysis (INAA) and fire assay-neutron activation (FA-NA) analysis. 5. RGS_ICPMS - all samples analyzed by inductively coupled plasma mass spectrometry (ICPMS). 6. RGS_All - includes all AAS, INAA and ICPMS data. Collection of stream sediment samples in Yukon began in 1976 and ended in 2006. Three analytical methods have been used to analyze the minus 0.177 mm fraction (-80 mesh) of these samples: AAS, INNA (and FA-NA) and ICPMS. A simple description of each method is given below.For atomic absorption spectrometry (AAS) a 1 g aliquot is 'partially digested' using Lefort aqua regia or concentrated hot nitric acid. The digestion product is analyzed using an atomic absorption spectrometer. Oxide and silicate minerals are partially digested while some sulphide minerals are erratically volatilized. This means that AAS cannot be used to obtain accurate REE, Ta, Nb, As, Sb, Sn, Hg, Cr, or Au determinations.For instrumental neutron activation analysis ( INAA), aliquots of sieved sediment (the minus 0.177 mm fraction) or milled rock ranging from 5 to 40 g are encapsulated and irradiated in a nuclear reactor before counting the primary gamma radiation induced by the neutron irradiation with a high resolution germanium gamma ray detector. Fire assay-neutron activation (FA-NA) analysis is similar but includes a pre-concentration fire assay step prior to irradiation and analysis. Results for both INAA and FA-NA are similar to those for samples analyses by fusion or other total digestion techniques. Neutron activation detection limits are typically higher than those by acid digestion - ICPMS. Commodity and pathfinder elements such as Au, As, Sb and W have reasonable detection limits by INAA and the data generated are relatively precise.For ICPMS analysis, aliquots of sieved sediment ( the minus 0.177 mm fraction) ranging from 0.5 to 1 g are prepared using a partial digestion technique, typically aqua regia, followed by analysis of dissolution product by ICPMS. Sulphide minerals are completely oxidized and dissolved whereas most oxide and silicate minerals are only partially digested. This means that results produced by partial digestion methods are acceptable for elements such as Ag, As, Mo, Ni, Pb, Sb, Tl, and Zn but values for elements such as Al, Ba, Cr, Fe, P, Sn, Ti, Y, and Zr are likely to not reflect the actual element concentration in a sample. The sample size used for routine RGS sample analysis is too small be representative of Au in the original sample and thus Au by aqua regia digestion - ICPMS has poor precision.Further upgrades to this database are not anticipated. All samples that could be found in the GSC-Ottawa warehouse have been reanalyzed using ICPMS. Any errors or omissions in this database should be reported to the Yukon Geological Survey. Your feedback contributes to improving the accuracy of the geoscience databases for Yukon.Contact: [YGSMinerals@yukon.ca](mailto:YGSMinerals@yukon.ca) ; [geology@yukon.ca](mailto:geology@yukon.ca)Distributed from [GeoYukon](https://yukon.ca/geoyukon) by the [Government of Yukon](https://yukon.ca/maps) . Discover more digital map data and interactive maps from Yukon's digital map data collection.For more information: [geomatics.help@yukon.ca](mailto:geomatics.help@yukon.ca)

Regional stream sediment geochemical data compilationNovember 2020Release notesThe regional stream sediment geochemical data compilation comprises data for more than 30 000 samples across Yukon. This compilation updates the work of Héon (2003). This new compilation includes results from the reanalysis of more than 24 000 samples; inductively coupled plasma mass spectrometry (ICPMS) analysis provides upgraded detection limits and a broader range of elements relative to previous analytical data. In addition to analytical data, efforts have been made to improve sample location accuracy. The data in this release are organized by analytical method with the geodatabase having six feature classes:1. RGS_SITE_WATER - site specific physiography and water quality data. These data are unchanged from the original releases. 2. RGS_HEON - the same data as released in Héon (2003) with minor updates to sample location. 3. RGS_AAS - all samples analyzed by atomic absorption spectrometry. Most of these data are superseded by INAA and ICPMS data. 4. RGS_INAA - all samples analyzed by instrumental neutron activation analysis (INAA) and fire assay-neutron activation (FA-NA) analysis. 5. RGS_ICPMS - all samples analyzed by inductively coupled plasma mass spectrometry (ICPMS). 6. RGS_All - includes all AAS, INAA and ICPMS data. Collection of stream sediment samples in Yukon began in 1976 and ended in 2006. Three analytical methods have been used to analyze the minus 0.177 mm fraction (-80 mesh) of these samples: AAS, INNA (and FA-NA) and ICPMS. A simple description of each method is given below.For atomic absorption spectrometry (AAS) a 1 g aliquot is 'partially digested' using Lefort aqua regia or concentrated hot nitric acid. The digestion product is analyzed using an atomic absorption spectrometer. Oxide and silicate minerals are partially digested while some sulphide minerals are erratically volatilized. This means that AAS cannot be used to obtain accurate REE, Ta, Nb, As, Sb, Sn, Hg, Cr, or Au determinations.For instrumental neutron activation analysis ( INAA), aliquots of sieved sediment (the minus 0.177 mm fraction) or milled rock ranging from 5 to 40 g are encapsulated and irradiated in a nuclear reactor before counting the primary gamma radiation induced by the neutron irradiation with a high resolution germanium gamma ray detector. Fire assay-neutron activation (FA-NA) analysis is similar but includes a pre-concentration fire assay step prior to irradiation and analysis. Results for both INAA and FA-NA are similar to those for samples analyses by fusion or other total digestion techniques. Neutron activation detection limits are typically higher than those by acid digestion - ICPMS. Commodity and pathfinder elements such as Au, As, Sb and W have reasonable detection limits by INAA and the data generated are relatively precise.For ICPMS analysis, aliquots of sieved sediment ( the minus 0.177 mm fraction) ranging from 0.5 to 1 g are prepared using a partial digestion technique, typically aqua regia, followed by analysis of dissolution product by ICPMS. Sulphide minerals are completely oxidized and dissolved whereas most oxide and silicate minerals are only partially digested. This means that results produced by partial digestion methods are acceptable for elements such as Ag, As, Mo, Ni, Pb, Sb, Tl, and Zn but values for elements such as Al, Ba, Cr, Fe, P, Sn, Ti, Y, and Zr are likely to not reflect the actual element concentration in a sample. The sample size used for routine RGS sample analysis is too small be representative of Au in the original sample and thus Au by aqua regia digestion - ICPMS has poor precision.Further upgrades to this database are not anticipated. All samples that could be found in the GSC-Ottawa warehouse have been reanalyzed using ICPMS. Any errors or omissions in this database should be reported to the Yukon Geological Survey. Your feedback contributes to improving the accuracy of the geoscience databases for Yukon.Contact: [YGSMinerals@yukon.ca](mailto:YGSMinerals@yukon.ca) ; [geology@yukon.ca](mailto:geology@yukon.ca)Distributed from [GeoYukon](https://yukon.ca/geoyukon) by the [Government of Yukon](https://yukon.ca/maps) . Discover more digital map data and interactive maps from Yukon's digital map data collection.For more information: [geomatics.help@yukon.ca](mailto:geomatics.help@yukon.ca)

Regional stream sediment geochemical data compilationNovember 2020Release notesThe regional stream sediment geochemical data compilation comprises data for more than 30 000 samples across Yukon. This compilation updates the work of Héon (2003). This new compilation includes results from the reanalysis of more than 24 000 samples; inductively coupled plasma mass spectrometry (ICPMS) analysis provides upgraded detection limits and a broader range of elements relative to previous analytical data. In addition to analytical data, efforts have been made to improve sample location accuracy. The data in this release are organized by analytical method with the geodatabase having six feature classes:1. RGS_SITE_WATER - site specific physiography and water quality data. These data are unchanged from the original releases. 2. RGS_HEON - the same data as released in Héon (2003) with minor updates to sample location. 3. RGS_AAS - all samples analyzed by atomic absorption spectrometry. Most of these data are superseded by INAA and ICPMS data. 4. RGS_INAA - all samples analyzed by instrumental neutron activation analysis (INAA) and fire assay-neutron activation (FA-NA) analysis. 5. RGS_ICPMS - all samples analyzed by inductively coupled plasma mass spectrometry (ICPMS). 6. RGS_All - includes all AAS, INAA and ICPMS data. Collection of stream sediment samples in Yukon began in 1976 and ended in 2006. Three analytical methods have been used to analyze the minus 0.177 mm fraction (-80 mesh) of these samples: AAS, INNA (and FA-NA) and ICPMS. A simple description of each method is given below.For atomic absorption spectrometry (AAS) a 1 g aliquot is 'partially digested' using Lefort aqua regia or concentrated hot nitric acid. The digestion product is analyzed using an atomic absorption spectrometer. Oxide and silicate minerals are partially digested while some sulphide minerals are erratically volatilized. This means that AAS cannot be used to obtain accurate REE, Ta, Nb, As, Sb, Sn, Hg, Cr, or Au determinations.For instrumental neutron activation analysis ( INAA), aliquots of sieved sediment (the minus 0.177 mm fraction) or milled rock ranging from 5 to 40 g are encapsulated and irradiated in a nuclear reactor before counting the primary gamma radiation induced by the neutron irradiation with a high resolution germanium gamma ray detector. Fire assay-neutron activation (FA-NA) analysis is similar but includes a pre-concentration fire assay step prior to irradiation and analysis. Results for both INAA and FA-NA are similar to those for samples analyses by fusion or other total digestion techniques. Neutron activation detection limits are typically higher than those by acid digestion - ICPMS. Commodity and pathfinder elements such as Au, As, Sb and W have reasonable detection limits by INAA and the data generated are relatively precise.For ICPMS analysis, aliquots of sieved sediment ( the minus 0.177 mm fraction) ranging from 0.5 to 1 g are prepared using a partial digestion technique, typically aqua regia, followed by analysis of dissolution product by ICPMS. Sulphide minerals are completely oxidized and dissolved whereas most oxide and silicate minerals are only partially digested. This means that results produced by partial digestion methods are acceptable for elements such as Ag, As, Mo, Ni, Pb, Sb, Tl, and Zn but values for elements such as Al, Ba, Cr, Fe, P, Sn, Ti, Y, and Zr are likely to not reflect the actual element concentration in a sample. The sample size used for routine RGS sample analysis is too small be representative of Au in the original sample and thus Au by aqua regia digestion - ICPMS has poor precision.Further upgrades to this database are not anticipated. All samples that could be found in the GSC-Ottawa warehouse have been reanalyzed using ICPMS. Any errors or omissions in this database should be reported to the Yukon Geological Survey. Your feedback contributes to improving the accuracy of the geoscience databases for Yukon.Contact: [YGSMinerals@yukon.ca](mailto:YGSMinerals@yukon.ca) ; [geology@yukon.ca](mailto:geology@yukon.ca)Distributed from [GeoYukon](https://yukon.ca/geoyukon) by the [Government of Yukon](https://yukon.ca/maps) . Discover more digital map data and interactive maps from Yukon's digital map data collection.For more information: [geomatics.help@yukon.ca](mailto:geomatics.help@yukon.ca)

Hydrogeological Regions provide a framework to introduce the regional hydrogeology of Canada and to connect apparently disparate studies into a broader framework. The hydrological regions are first order areas used to capture and summarize data that will help develop more detailed profiles of each region. Comparison of findings within and between regions will allow scalable extension to sub-regional and watershed scale mapping.Canada has been classified into nine principal hydrogeological regions. Each region is described briefly based on the following five hydrogeological characteristics (Heath, 1984):system components and geometry;water-bearing openings;rock matrix composition;storage and transmission;recharge/ discharge.The hydrogeological classification emphasizes major geological provinces and rock formations. Fundamental water-bearing openings and rock matrix properties help determine the quantity (storage), flux (transmission), and composition of formation waters. These same properties and any overlying sediment cover affect recharge/ discharge rates for regional formations. While regional attributes are general, a simple aquifer mapping scheme can further describe the nature and character of aquifers in each region. For example, general groundwater settings across the country could be described as has been done by USGS principal aquifers [1]. Thus the regional framework can potentially link from national scales to watershed scales by identifying typical aquifer types based on readily available geological maps that use water-bearing character as a common attribute.The nine hydrogeological regions include:CordilleraMountains with thin sediment over fractured sedimentary, igneous and metamorphic rocks of Precambrian to Cenozoic age. Intermontane valleys are underlain by glacial and alluvial deposits of Pleistocene age.Plains (Western Sedimentary Basin)Region-wide basin of sub-horizontal Paleozoic to Cenozoic sedimentary rocks are overlain by thick glacial deposits filling buried valleys. Incised post-glacial valleys provide local relief. Shallow gas, coal, and brines may occur.Canadian ShieldUndulating region of thin glacial sediment overlying complex deformed, fractured PreCambrian igneous, metamorphic and sedimentary rocks. Region contains several terrains: sedimentary basins, structural belts, and glacial-lacustrine basins.Hudson Bay (Moose River) BasinSedimentary basin of Paleozoic to Mesozoic sub horizontal carbonate and clastic sediment covered by surficial deposits, with low relief and poor drainage.Southern OntarioEastern Great Lakes region is underlain by gently-dipping Paleozoic, carbonate, clastic and gypsum-salt strata overlain by glacial sediments up to 200 m thick with tunnel valleys. Karst, bedrock valleys, shallow gas and brines are also important components.St. Lawrence LowlandsLowlands underlain by shallow-dipping Paleozoic sedimentary rocks and thick glacial sediment in glacial-marine basins. Appalachian and Precambrian uplands discharge water to valleys. Shallow gas and saltwater intrusion are possible.AppalachiaUpland to mountainous region with thin surficial sediment on folded Paleozoic sedimentary and igneous rocks. Range of rock types yields a wide range of water compositions. Valleys contain important alluvial aquifers.Maritimes BasinLowlands with flat-lying, Carboniferous clastic , salt, and gypsum rocks contain shallow coal deposits. Surface glacial sediment is thin and discontinuous. Salt water intrusion is possible.PermafrostArctic islands and most areas north of 60o contain frozen ground affects on groundwater flow. Diverse topography and geology define sub-regions of sedimentary basins and crystalline rocks. Glacial sediment is thin, discontinuous; local peat accumulations are significant.