Stratigraphic Nomenclature

The rocks of Atlantic Canada represent almost a billion years of history and record the tectonic events that have
shaped this planet and this region. From mountain building collisions of continents to rifting that split apart the
supercontinent Pangea, it is all recorded in the rocks.
In this assignment we will take a look at the ages and types of some of the rocks that form Nova Scotia. We will be
working with the Geology Map of Nova Scotia. This publication contains an amazing amount of information and is
recommended for anybody interested in the rocks and geological history of this province. But before we can start
we have to understand how to read a geological map.
How Rocks are Named
To identify layers of rock, geologists have created several categories to distinguish one rock layer from another.
The basic unit in this system of classification is the formation. Often this will be abbreviated to Fm. in usage. The
Halifax Formation, or Halifax Fm. for example. A formation is a rock unit that has a distinctive appearance; a
geologist can tell it apart from the rock layers around it. Formations will usually have one distinctive type of rock,
the Halifax Formation is predominately slate, but they may often include a variety of rock types. Formations must
also be thick enough and extensive enough to plot on a map.
Formations can also be subdivided into smaller units called members (Mb).
Formations can also be lumped together into larger units called groups (Gp). The Meguma Group is comprised of
the Halifax and Goldenville Formations.
Members make up formations. Formations make up groups.
When geologists propose a new name, they must publish a formal description that includes a full description of the
rock unit and the location of the type locality. The procedures for classifying and naming rock units are contained
in the North American Stratigraphic Code, prepared by the North American Commission on Stratigraphic
Nomenclature. All unit names are formal and should be capitalized in use.
Map Reading
Geological maps are overflowing with information but you have to know how to extract it. The rock units
(members, formations, and groups) are indicated with different colours and symbols. The age of the unit is often
conveyed by the stylized letter that represents a specific period in the geologic time scale. A unit that spans more
than one period in age will have both letters.
This symbol indicates that this unit is of Devonian – Carboniferous age (DC).
The smaller letters following refer to the unit name (or in some cases the rock type) – in this case
the Fountain Lake Group.
Sometimes a smaller letter will precede the age indicating the epic; for example, E-early, M-middle, L-late.
All this information is recorded in the map legend.
Next to the symbol there will be a description of the unit t

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