 In the scientific world , several of his descriptive passages generated excitement and curiosity . In early 1914 , he had been surveying a portion of the international boundary in the Upper Waria River between the German and British protectorates . By late September , he had passed into a different portion of the highlands , where the clay @-@ slate mountains changed into limestone highlands . In this geologic transition , he said , he also found a change in the ethnographic character of the population , whom he described as a " new " people . They were stocky , powerfully built , and long – limbed ; they wore their hair in knots on the centre of their heads , which were otherwise shaven , and painted yellow and black lines across their chests . They also wore grass skirts , so he called them the skirted ones . They used bows and arrows , slings and stone axes . As he pushed west to Mount Joseph , Detzner claimed , he had found the southern hills of the central watershed cut by numerous rivers flowing north to south . He had surmised that there were no insurmountable obstacles between him and the Sepik river . In 1917 , he had travelled through the Ramu valley into the Bismarck range , northwest of the Kratke Mountains , and had continued on that route for 100 kilometres ( 62 mi ) . He also described the presence of an indigenous variation of German , called Unserdeutsch ( our German ) , in several New Guinean dialects . 
