Left: SiO sub 4 tetrahedra. Basic unit of all silicate structure. Right: Si sub 2 O sub 7 (double Tetrahedral group). In silicate structures the silicon atoms group in fourfold symmetry with oxygen. The basic unit of all silicate structure is the tetrahedron. The sorosilicates possess double tetrehedral groups.

Chain structures for amphiboles and pyroxenes (left). Silicon-oxygen tetrahedra form simple or double chains in the inosilicates by sharing oxygen atoms with neighbouring tetrahedra.

Muscovite. Oxygen: white. Silicon: small metallic spheres in centre of white tetrahedral oxygen groups, only one or two visible. Aluminum: larger metallic spheres. Potassium: purple OH groups, or hydroxyl: blue. A phyllosilicate.

Fault scarp cutting throuh school, Anchorage.

Open crack, minor scarps, Anchorage.

Rockfall and differential weathering (Eckel, 1958, p. 22).

Four varieties of slumping (Eckel, 1958, p. 25).

Block glide (Eckel, 1958, p. 31).

Crack pattern of slump slide in cohesive material (Eckel, 1958, p. 55).

Landslide near Hope, B.C., covering Hope-Princeton highway. January 1965

Conceptual scheme for the evolution of landscape in a humid temperature climate. The transition from, late youth ti early maturity is marked by the disappearance of remnants of the initial surface and by smoothing (grading) of valley side-slopes. In early maturity, most of the landscape is occupied by valley side-slope; in late maturity, by the valley flats of streams. The dashed line on each block represents sea level.

Buckling associated with strike-slip faulting. Billings, 1960, p. 393.

Map of southeastern Pennsylvania and eastern Maryland showing sedimentary rocks of Newark group, and dikes and sills of diabase which intrude both the Newark group and the earlier crystalline and sedimentary rocks of surrounding areas. King 1959, p. 51.

Block diagram showing stages of erosion of a mountain in the Basin and Range province. An initial fault-block form is assumed in stage A, but successing stages might have developped from any initial tectonic form. (A) Fan-free and Fan-based, (B) Fan-dented, (C) Fan-bayed, (D) Fan-frayed, (E) Fan-wrapped, (F) Pan-fan. King 1959, p. 155.

Laminar and turbulent flow in stream. Velocity is indicated by the relative length of the flow lines. Dunbar and Rodgers, 1957, p. 5.