Glacial grooves can be found on most outcrops in the southern part of Central Park, transecting the structures of the schist bedrock. The thinnest grooves are the width of pencils and are little bigger than striations or glacial scratches. The larger grooves are more than 30 cm wide and extend for several metres across rock surfaces. The grooves are best developed on the up-ice slopes of roches moutonnées, where ice was forced to move uphill and where the resultant pressures intensified on the pulverising blocks moving across the rock floor.