Measuring a stratigraphic section in Tertiary red beds along the highway near Boqueron del Padre Abad. From left to right: Amanzio Caldas, Jorge Portugal, Bernhard Felber, Dave Keppel (Allan Craig on outcrop).

Axel Heiberg Gr. Meandering meltwater channels on ice of glacier near station 63 K 120, dropping down over debris-laden margin.

Meander scrolls in the Assiniboine River valley. Near Treat, Manitoba. October 5, 1962.

Meander scar behind McCauleyville beach, Lake Agassiz east of Grand Forks, N.D. to show low saddle where cut-off took place. Continuation of slide #99, looking farther to the east. May, 1962.

Meander scar behind McCauleyville beach, Lake Agassiz east of Grand Forks, N.D. to show low saddle where cut-off took place. May, 1962.

McConnell thrust fault. Precambrian (cliff) thrust over Belly River (white slope) of Upper Cretaceous age. Mount Yamnuska, near Banff, Alberta

McConnell thrust fault. Precambrian (cliff) thrust over Belly River (white slope) of Upper Cretaceous age. Mount Yamnuska, near Banff, Alberta

Mature dune-forms and their formation. I. Mature dunes. II. Stage of rejuvenation. 1. Blow-out dunes. 2. Lee dunes. 3. Windward dune. III. Stage of deflation. 4. Deflation-plain. 5. Deflation-lake. 6. Remnant-dune. 7. Talus. 8. Young "white" dune. These dune types are common in old littoral dunes as well as old continental dunes. Source: Atlas of Denmark.

Mastodon and mammoth teeth. Above, a sideview of a tooth of a mastodon showing the paired cusps; below, a top vier of a tooth of an elephant or mammoth showing the infolding of the enamel to strengthen the tooth for grazing. The scales are in centimeters (After Clark and Stearn, 1960, p. 375).

Mars. Note ice cap.

Marl exposure along river bank. North side of Sturgeon River about 300 feet west of bridge on south end of Sturgeon Lake, Sask.

Marine cliff with pebble beach in front. Note beach cusps, poorly developed. Black material on beach is kelp. Note contact between White Chalk, Sevonian, below and Danian limestone above. Stevns Klint, Island of Sjaelland, Denmark. Monday, August 22, 1960.

Margin of lava flow of 1875, Nyjarhaun, east of Myvatn. August 5, 1960.

Marble quarries near Carrara, Italy.