Origin of glacial curvilineations by subglacial meltwater erosion: Evidence from the Stargard drumlin field, Poland

TY - JOUR

T1 - Origin of glacial curvilineations by subglacial meltwater erosion:

T2 - Evidence from the Stargard drumlin field, Poland

AU - Hermanowski, Piotr

AU - Piotrowski, Jan A.

N1 - Funding Information: The study was supported by the Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, internal grant to PH and grant no. DFF‐7014‐00156 from the Danish Council for Independent Research to JAP. Publisher Copyright: © 2022 John Wiley & Sons Ltd.

PY - 2023/2

Y1 - 2023/2

N2 - Deciphering the origin of subglacial landforms is crucial for understanding processes operating under ice sheets. Due to the inaccessibility of the ice/bed interface limiting real-time observations, the origin of these landforms is typically interpreted from the morphological and sedimentological record exposed after ice retreat, which makes the conclusions conjectural. Here, we focus on a recently discovered new type of subglacial landform called glacial curvilineations (GCLs), whose formation generates some controversy. We use LiDAR imagery and geological data to constrain the origin of GCLs found in a tunnel valley in the Stargard drumlin field, Poland. The tunnel valley is about 3800 m long, 520 m wide, and it occupies about 2 km2. A total of 61 individual GCLs have been mapped there; they are up to 550 m long and typically 0.5–1.5 m high, but some reach a height of up to 5 m. The GCLs are composed of mostly massive till represented by either a single or several diamicton units occasionally separated by thin layers of meltwater sand. Till macrofabrics in the GCLs and in the nearby till plain are distinctly consistent, and have high and uniform clustering strengths. At all locations, the dominant till fabric direction broadly corresponds with the ice movement direction given by the drumlin orientations, but it is oblique to the orientation of the tunnel valley and independent of the orientations of the individual GCLs. The lack of correspondence between the orientation of the GCLs and the till fabrics in them suggests that the GCLs consist of an antecedent till deposited during the drumlinizing ice advance and subsequently carved by subglacial meltwater erosion in the tunnel valley. These results substantiate the hypothesis that GCLs are erosional features postdating the material constituting them, and emphasize the role of subglacial meltwater flows as a landforming agent.

AB - Deciphering the origin of subglacial landforms is crucial for understanding processes operating under ice sheets. Due to the inaccessibility of the ice/bed interface limiting real-time observations, the origin of these landforms is typically interpreted from the morphological and sedimentological record exposed after ice retreat, which makes the conclusions conjectural. Here, we focus on a recently discovered new type of subglacial landform called glacial curvilineations (GCLs), whose formation generates some controversy. We use LiDAR imagery and geological data to constrain the origin of GCLs found in a tunnel valley in the Stargard drumlin field, Poland. The tunnel valley is about 3800 m long, 520 m wide, and it occupies about 2 km2. A total of 61 individual GCLs have been mapped there; they are up to 550 m long and typically 0.5–1.5 m high, but some reach a height of up to 5 m. The GCLs are composed of mostly massive till represented by either a single or several diamicton units occasionally separated by thin layers of meltwater sand. Till macrofabrics in the GCLs and in the nearby till plain are distinctly consistent, and have high and uniform clustering strengths. At all locations, the dominant till fabric direction broadly corresponds with the ice movement direction given by the drumlin orientations, but it is oblique to the orientation of the tunnel valley and independent of the orientations of the individual GCLs. The lack of correspondence between the orientation of the GCLs and the till fabrics in them suggests that the GCLs consist of an antecedent till deposited during the drumlinizing ice advance and subsequently carved by subglacial meltwater erosion in the tunnel valley. These results substantiate the hypothesis that GCLs are erosional features postdating the material constituting them, and emphasize the role of subglacial meltwater flows as a landforming agent.

KW - erosional forms

KW - glacial curvilineations

KW - Scandinavian Ice Sheet

KW - subglacial processes

KW - tunnel valleys

UR - http://www.scopus.com/inward/record.url?scp=85139399113&partnerID=8YFLogxK

U2 - 10.1002/esp.5485

DO - 10.1002/esp.5485

M3 - Journal article

AN - SCOPUS:85139399113

SN - 0197-9337

VL - 48

SP - 282

EP - 294

JO - Earth Surface Processes and Landforms

JF - Earth Surface Processes and Landforms

IS - 2

ER -