Title

Till Fabric

Date of Award

1958

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Geology

First Advisor

F. D. Holland Jr

Abstract

Till fabric was noticed as early as 1859. Several geologists described it in the latter part of the nineteenth century. However, the concept of a fabric in till was not generally accepted until 1932 when Konrad Richter noted a preferred orientation of till particles in Northern Germany. He supported his findings with statistical data. Comprehensive studies were published by W. C. Krumbein and especially C. D. Holmes a few years later. Extensive work on the subject was conducted by several geologists in the 1950’s.

Till fabric is classified as macrofabric and microfabric. The latter is further classified as (1) microfoliation, (2) coarse fragment orientation, and (3) veining.

Several methods used in collecting and measuring the orientation of the particles are discussed. In most cases the particles are reoriented in the laboratory.

The data may be plotted either on a “rose diagram” or the conventional “petrofabric diagram.” The former allows only the azimuths of the particle axes to be plotted while both the azimuths and dips may be plotted on the latter.

The long axes of till particles is commonly oriented parallel to the direction of glacier flow. However, several geologists have found a transverse orientation of these axes. The shape, roundness, and amount of axial dip of the particle determines its orientation.

Several theories as to the genesis of till fabric are discussed. It is concluded that the theory which is proposed by Holmes is the most acceptable. Parallel orientation of the long axis is believed to be due to a sliding movement of the particle and the transverse orientation to a rotating movement.

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