 The earthen mound that once covered the tomb is now visible only as an <unk> approximately 1 foot , 6 inches in height . In the nineteenth @-@ century , the mound was higher on the western end of the tomb , although this was removed by excavation to reveal the sarsens beneath during the 1920s . It is likely that in the Early Neolithic , the mound had a quarry ditch surrounding it , and it is inside this ditch that the kerb @-@ stones now sit . 
