Evidence of Fractures in NPLD and Their Significance to the Formation of Martian Polar Spiral Troughs.

Introduction : Understanding the structure and stratigraphy of polar ice is an integral part of unraveling the history of its formation and implications for past and present climate [e.g., 1, 2]. Earlier studies of the North Polar Layered Deposits (NPLD) in Planum Boreum on Mars have provided valuable insight into the nature of these materials [3]. Radar sounding results show angular unconformities within the NPLD that are interpreted as erosional periods within climatological cycles [4]. Here, we present evidence of fractures in the NPLD based on interpretation of MOC images and radar sounding data, and we discuss the significance of these fractures to the formation of Martian polar spiral troughs.