Athro, Limited Gubik Field Trip Section 20 Karmuk

You are standing about 3/4 of the way up the cliff (dark blue arrow), looking in the direction of the green arrow. This is near the base of your trench (light blue arrow).

Interpreted view of contact Close up is below.

The contact between the underlying folded sediments and overlying flat-lying sediments is exposed here. It is clearly an angular unconformity, indicating that the underlying sediments were deformed and eroded prior to the deposition of the overlying sediments.

The erosional surface is not flat. It has a relief of some 10 cm. Immediately overlying the erosional surface is a concentration of pebbles, a lag deposit.

Contact

The rock hammer marks the unconformity. The knife marks the top of a dark brown clay that drapes the erosonal surface. There is a pebble lag at the base of this clay, and scattered fossil mollusc shells in it. The clay is overlain by interbedded fine sands and clays.

Move up to look at:
• Sands higher in section
• Shell bed lower in section
• Shells low in section
• Contact with Folded Sediments at base of section