Till

Till or glacial till is unsorted glacial sediment.

Till is derived from the erosion and entrainment of material by the moving ice of a glacier. It is deposited some distance down-ice to form terminal, lateral, medial and ground moraines.

Till is classified into primary deposits, laid down directly by glaciers, and secondary deposits, reworked by fluvial transport and other processes.

Processes

Glacial drift is the coarsely graded and extremely heterogeneous sediment of a glacier; till is the part of glacial drift deposited directly by the glacier. Its content may vary from clays to mixtures of clay, sand, gravel, and boulders. This material is mostly derived from the subglacial erosion and entrainment by the moving ice of the glaciers of previously available unconsolidated sediments. Bedrock can also be eroded through the action of glacial plucking and abrasion and the resulting clasts of various sizes will be incorporated to the glacier's bed.

Eventually, the sedimentary assemblage forming this bed will be abandoned some distance down-ice from its various sources. This is the process of glacial till deposition. When this deposition occurs at the base of the moving ice of a glacier, the sediment is called lodgement till. Rarely, eroded unconsolidated sediments can be preserved in the till along with their original sedimentary structures. More commonly, these sediments lose their original structure through the mixture processes associated with subglacial transport and they solely contribute to form the more or less uniform matrix of the till.

Steg

Steg may refer to:

Frost

Frost is the coating or deposit of ice that may form in humid air in cold conditions, usually overnight. In temperate climates it most commonly appears as fragile white crystals or frozen dew drops near the ground, but in cold climates it occurs in a greater variety of forms. Frost is composed of delicate branched patterns of ice crystals formed as the result of fractal process development.

Frost is known to damage crops or reduce future crop yields, therefore farmers in those regions where frost is a problem often invest substantial means to prevent its formation.

Introduction

Frost forms when the temperature of a solid surface in the open cools to below the freezing point of water and for the most clearly crystalline forms of frost in particular, below the frost point in still air. In most temperate countries such temperatures usually are the result of heat loss by radiation at night, so those types of frost sometimes are called radiation frost.

Types of frost include crystalline hoar frost from deposition of water vapor from air of low humidity, white frost in humid conditions, window frost on glass surfaces, advection frost from cold wind over cold surfaces, black frost without visible ice at low temperatures and very low humidity, and rime under supercooled wet conditions.