Image is of a rugged coastline with low waves lapping onto shelving rocks in the foreground. In mid-frame, a group of five persons can be seen traversing a boulder-strewn inner shore, and in the background low, snow-covered cliffs rise to a clear blue sky.

Three warmly dressed people are standing in the mid-distance on an undulating surface of exposed limestone beds. Behind them is a vertical cliff about 10 metres high, exposing a section through weathered limestone strata. Snow covers part of the exposure on the left and in the mid-ground. Just above and to the right of the trio of geologists, the limestone layers are bowed gently upwards overlying a mound-shaped mass formed of the fossil remains of an extinct group of calcareous sponges known as archaeocyathans. This is an example of an early skeletal "reef" -- a wave resistant structure built on the Cambrian sea floor.

Back to #Newfoundland&Labrador for #Strataday, this time in #Labrador itself: #Cambrian (~515 MYA) Forteau Fm limestones, N shore of Strait of Belle Isle, E of Point Amour. Large mound-like structures are skeletal "reefs" built by #archaeocyathan #sponges. Slide scans from #fieldwork in June 1976.