The thesis examines the evidence for geomorphic activity of avalanches in the Cairngorm Mountains, Scotland. A typical avalanche boulder tongue morphology is developed from the literature. The form will have the following characteristics: concave slope profile, the top of the form will be in exposed bedrock, the form will be fan shaped or road bank type tongue which extends beyond the main break of slope and is raised above the surrounding surface of the valley, debris will be strewn over the tongue especially in the deposition zone and microrelief features are present on different zones of the tongue (missing boulder hole, bump holes, debris tails, scratch marks and perched boulders). The field work shows that these features do occur in the study area and furthermore that two other types of avalanche modified forms are present. These are: avalanche swept slopes where the avalanche clears the slope of debris, depositing it at the furthest extent of the avalanche activity and avalanche plunge pools where the avalanche terminates in water and deposits debris in a crescentic shape, under water, at the outer limit of the avalanche's reach. From the evidence gathered in the field the typical avalanche modified slope for the Cairngorm area is developed, describing the morphology of each subtype of form found. Other minor forms are also found in the study area: avalanche garlands. These forms are small garlands of debris that are deposited at the base of a gully along the side of the slope. These are created by snow sluffs entraining debris a short distance down the slope and clearing the area immediately surrounding the gully. The thesis subsequently examines the variables that control the formation of these forms and statistical analysis is used to examine these variables and their importance in controlling the development of the form. This data is also used to calculate the probability of avalanche modified slopes forming in the study area.