11 
The most important of the basic eruptives is peridotite, generally 
transformed to serpentine. The largest area is that of mount Albert, just 
west of the Tabletop granite mass. It is elongated from east to west and, 
as shown on the map, extends for 18 miles along the southern side of the 
main range of the Shickshocks near the headwaters of Ste. Anne and 
Cascapedia rivers. There are also small bosses of serpentine shown on 
the map on Dartmouth river, southwest of the village of Fox River; and 
near cap D’Espoir, Serpentine weathers rapidly and, therefore, is not as 
useful as granite for glacial work, but the outcrops are so located as to be 
of importance in determining the direction of ice motion. 
Porphyrite of a basic kind (probably diabase porphyrite), sometimes 
associated with amygdaloidal phases, occurs as hills along the north shore 
of Chaleur bay, often forming the actual coast. The position of these 
areas makes them of little importance from the present point of view; 
but the amygdaloid found on the southeastern part of lake Matapedia, 
as mentioned above, though not shown on the map, is of considerable 
interest. 
Having referred briefly to the distribution of rocks in place it is now 
possible to understand, the significance of the boulders of one kind or 
another occurring in boulder clay or as erratics. 
It may be said in concluding this part of the work that typical Lauren- 
tilth, Keewatin, and Grenville rocks are nowhere found in Gaspe, so that 
boulders of them must have been derived from the great Archaean area 
north of the St. Lawrence. 
GLACIAL PHENOMENA 
Work on Floating Ice 
Every traveller along the north shore of Gaspe is struck by the great 
numbers and large size of- the boulders on the shore. These include many 
varieties of granite, gneiss, and pegmatite and also anorthosite, gabbro, 
green schists, and occasionally crystalline limestone. They are travelled 
stones derived from the north shore of the St. Lawrence, and their size, 
often reaching diameters of 10 feet or more, compels one to account for 
their presence by ice transport. There are three ways in which this may 
have occurred: (a) by the southward spread of the Labrador ice-sheet; 
(b) by the aid of icebergs when the land stood lower; (c) by floe ice enclosing 
boulders along shore and drifting with them across the St. Lawrence. 
The probability is that all three modes of transport have at some time 
been in operation; the last one perhaps still being to some extent effective. 
The geologists who have specially referred to these boulders, Bell and 
Chalmers, support the iceberg theory of transport during a late Pleistocene 
time of depression of the land. 
Blocks such as these become less frequent towards the east along the 
north coast of Gaspe and are rare on the south coast along Chaleur bay, 
as is natural if they came from north of the St. Lawrence. 
Although boulders of foreign rocks are most numerous and striking 
along the present shore, they occur also on the marine terraces that rise 
inland; but above the highest ancient sea-levels they are no longer found, 
as noted by previous geologists and confirmed by the writer. Evidently, 
the ice that brought them could not lift them above sea-level, which 
