Francis X. Ashland 20220523 vector digital data Reston, VA U.S. Geological Survey https://doi.org/10.5066/P92LZ8R2 Pluvials can have dramatic impacts on the shoreline bluffs of Lake Michigan due to increases in both shallow subsurface moisture conditions related to the prolonged wet weather pattern and wave erosion as the lake level rises. These changes can result in an increased frequency and magnitude of slope failures. During the most recent pluvial, the monthly average level of Lake Michigan rose 1.9 m from a record low in January 2013 to a near record high in June-July 2020. To assess the impacts on coastal bluffs from slope failures during the recent pluvial, an inventory of landslides was completed, including slope failures active during the early part of the pluvial, on the coastal bluffs of North Manitou Island, part of the Sleeping Bear Dunes National Lakeshore in Michigan. Landslides were mapped using high-resolution orthoimagery, collected in April 2012, and high-resolution topography derived from a LiDAR data set, collected in December 2014. This data release presents geographic information system (GIS) data, provided as line and polygon shapefiles (.shp), depicting landslides and related landforms and features. Polygon map data delineates the areas of deposits, source areas, and related landforms (such as alluvial fans and colluvial aprons). Scarps (such as headscarps and minor scarps) are presented as hachured line data. An attribute file is included providing a definition of the mapped units and a brief description of the approach used in the mapping. The purpose of this mapping was to create an inventory of historical (recent and pre-existing) landslides on the coastal bluffs of North Manitou Island in Lake Michigan, part of the Sleeping Bear Dunes National Lakeshore. High-resolution orthoimagery, dated April 4, 2012, and topography from a LiDAR data set collected in December 2014 were used to identify and map landslides and related features. The range in dates of the imagery temporally overlapped with the early part of a recent pluvial that resulted in 1.9 m rise in the monthly average level of Lake Michigan between January 2013 and July 2020. The areas of active slope movement identified using aerial imagery and topography, dated between April 2014 and December 2014, defined the extent and magnitude of landsliding directly prior to the onset of and during the early part of the recent pluvial and provided insight into the types and mechanisms of the slope failures. 20120404 20141223 observed In work As needed -86.0680 -85.9505 45.1630 45.0470 ISO 19115 Topic Category geoscientificInformation USGS Thesaurus landslides inventory map None landslide inventory LiDAR high resolution orthoimagery USGS Metadata Identifier USGS:6286cda1d34e4fef2ec3af36 Common geographic areas Sleeping Bear Dunes North Manitou Island Leelanau County Michigan None. Please see "Distribution Info" for details. None. Francis Ashland Northeast Region: FLORENCE BASCOM GEOSCIENCE CENTER Research Geologist mailing and physical

Mail Stop 926A, 12201 Sunrise Valley Dr

Reston VA 20192 US 703-648-6923 fashland@usgs.gov Data collection supported by USGS NRPP 2021-04. ArcGIS ArcMap 10.8.1 See Process Step description. See Process Step description. See Process Step description. Earth Resources Observation and Science (EROS) Center 2017 dataset https://www.sciencebase.gov U.S. Geological Survey The following imagery tiles were used: mi_sleeping_bear_dunes_premiergeo_20120404_00011_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00012_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00013_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00014_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00015_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00016_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00017_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00021_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00022_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00023_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00024_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00025_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00028_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00029_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00033_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00034_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00035_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00036_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00041_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00042_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00045_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00046_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00047_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00058_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00059_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00060_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00071_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00072_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00085_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00096_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00097_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00108_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00109_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00146_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00147_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00156_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00157_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00167_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00168_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00177_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00178_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00179_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00180_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00193_rgb_12inch mi_sleeping_bear_dunes_premiergeo_20120404_00194_rgb_12inch https://earthexplorer.usgs.gov/ Digital and/or Hardcopy 20120404 ground condition High Resolution Orthoimagery Forty-four (45) image tiles were used to identify and map landslide deposits, landforms, and related features U.S. Geological Survey 20200330 raster digital data Mosaic created from two tiles: USGS one meter x57y499 MI LeelanauCo 2015 USGS one meter x57y500 MI LeelanauCo 2015 USGS one meter x57y501 MI LeelanauCo 2015 USGS one meter x58y500 MI LeelanauCo 2015 https://apps.nationalmap.gov/viewer/ Digital and/or Hardcopy 20141206 20141223 ground condition Digital Elevation Model (DEM) 2015 These data were used to create high resolution topography (hillshade, slope map) to identify and map landslide deposits, landforms, and related features An inventory of landslides (deposits, complexes) and related features (scarps, source areas) and landforms (colluvial aprons, alluvial fans) was created using a combination of high-resolution topography and aerial imagery. The high resolution (1 m) topography used for the inventory mapping on North Manitou Island (NMI) was derived from a LiDAR data sets collected in December 2014. Most of the inventory mapping was performed on topography derived from the December 2014 data (LeelanauCo 2015) that consisted of a transparent hillshade, underlain by a slope map with 1-m contours. High resolution (0.3 m) orthoimagery, dated April 4, 2012 (2012 HRO), was used to identify and map recent slope failures that predated the rise in lake level. This specific aerial imagery was also the oldest historical imagery available on the Google Earth geographic browser with sufficient resolution to identify areas of recent landslide movement on the island. Two additional collections of historical imagery, dated May 30, 2015; and May 15, 2018; respectively, available on the Google Earth geographic browser were also used to identify the locations of landslides as well as the changes in boundaries of recent slope failures and topography during the recent pluvial and rise in lake level. Landslides and features identifiable on the May 2015 Google Earth imagery provided some guidance on the delineation of landslides and related features on the LeelanauCo 2015 topography and was specifically used to identify changes in scarp traces since April 4, 2012. The May 2018 aerial imagery was useful in identifying shoreline landslides formed in response to increased wave cutting due to the rising lake level up to that date. The more recent landslides were not mapped on NMI due to the island not being included on the Charlevoix Islands 2016 topography. Landslides identified on the LeelanauCo 2015 topography were subdivided based on morphological expression and information on recent activity derived from historical imagery available on the Google Earth geographic browser. NMI_2015DEP typically exhibited somewhat lobate lower boundaries characterized by convex contour lines, in plan view, and evidence of recent activity between April 2012 and December 2014. NMI_RDEP commonly exhibited similar topographic expression as NMI_2015DEP, but with evidence of movement within a few years to weeks prior to April 2012. NMI_ODEP shared similar characteristics to the other landslide deposits, at least in part, but lacked evidence of recent movement on historical imagery between April 2012 and May 2015. On coastal bluffs the age of these deposits is inferred to range between 1986 and 2012, but may be older on inland slopes. Complexes were mapped in commonly denuded areas where slope failures of various types, primarily slides and flows, were too closely spaced to differentiate and, in some cases, different failure types temporally overlapped in the same location. In most cases, slope failures in the complexes were inferred to be shallow in nature. Shallow landslide complexes (NMI_SLC) were mapped primarily where evidence of recent landslide movement was detected on either, or both, of the 2012 and 2015 aerial imagery. Older complexes (NMI_OSLC) were mapped where slopes ranged from completely forested to partly revegetated, but had similar, to perhaps slightly subdued, morphological expression of the more recent complexes on mostly denuded slopes (NMI_SLC). Areas of this description that directly abutted the NMI_SLC unit were sometime included in it. Recently denuded bluffs associated with landslide activity, but lacking evidence of recent (between April 2012-May 2015) slope failures, or where evidence of recent slope movement was either limited to specific areas within or to the perimeter of the complex were designated as NMI_RDSLC. In cases where flow-type slope failures appeared to be dominant, based on the presence of coalesced alluvial fans and closely spaced source area scars, were mapped as NMI_FDSLC or NMI_FDRDSLC. Complexes were delineated using both the LeelanauCo 2015 topography and 2012 HRO. The numerous shoreline alluvial fans (NMI_AF) were delineated primarily using the LeelanauCo 2015 topography with guidance from the May 2015 aerial imagery. Where more than two alluvial fans had coalesced the NMI_CAF map unit was used. The sources areas of the alluvial fans were mapped as two separate units depending on whether they consisted solely of narrow ravines or gullies (NMI_NFSA), or shallow landslide complexes (NMI_FSASLC) that typically occupied most of the headwater region of the drainage system upstream of the alluvial fan. The latter were typically separated from the apex of the alluvial fan by a flow travel path channel (NMI_FTPC). The transition from source area to travel path was commonly selected based on the concavity of the contour lines in the channel, specifically where concave contour lines change to planar. Scarp traces were differentiated by either relative or absolute age (NMI_2015SCARP, NMI_RSCARP, and NMI_OSCARP) and mapped using either the LeelanauCo 2015 topography (NMI_2015SCARP or NMI_OSCARP) or the 2012 HRO (NMI_RSCARP). NMI_2015SCARP traces were delineated where upslope of NMI_RSCARP traces or associated with NMI_2015DEP, based on comparison of historical imagery, dated April 2012 and May 2015. Older scarps (NMI_OSCARP) were inferred where no evidence of formation, or a change in position existed on recent historical imagery, or when associated with NMI_ODEP and are inferred to have formed between 1986 and 2012 on coastal bluffs. Pluvial scarps evident on the LeelanauCo 2015 topography (NMI_2015PSCARP) were induced by wave cutting during the recent (January 2013-December 2014) rise in lake level. Where slope failures were also induced and the deposit had not yet been eroded by December 2014, the undifferentiated denuded pluvial scarp and deposit was mapped as NMI_2015UDPSD. 20220520 Vector Universal Transverse Mercator 16 0.9996 -87.0 0.0 500000.0 0.0 coordinate pair 1.001079 1.001079 meters D_North_American_1983 GRS_1980 6378137.0 298.257222101 GS ScienceBase U.S. Geological Survey mailing and physical

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Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor should the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P92LZ8R2 None 20220523 Francis Ashland Northeast Region: FLORENCE BASCOM GEOSCIENCE CENTER Research Geologist mailing and physical

Mail Stop 926A, 12201 Sunrise Valley Dr

Reston VA 20192 US 703-648-6923 fashland@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998