Glaciology is a scientific field that studies all aspects of ice on landmasses. It examines the structure and properties of glacier ice, as well as its production and distribution, ice flow dynamics, and ice accumulation-climate interactions. Glaciological study is carried out using a range of techniques. Radar sounding is used to study the internal structure of glaciers, and the deformation of vertical boreholes or lateral tunnels bored into the ice is used to monitor glacier movement. Remote sensing data is used to estimate ice accumulation over wide areas, and oxygen isotope ratios are typically used to distinguish the distinct annual layers in glacier ice.