- 563 - 
rmine which 
monochrome 
getated 
Dssible to 
)hic labora- 
id 7 are 
, The 
'ared film, 
id, 6 = green, 
iressive. 
by unique 
able to 
may be 
ntly or 
s are rarely 
ocks, soil, 
from white 
of rocks and 
film is 
study of 
i-vegetated 
fc than the 
subjects, 
?en its 
Free water, 
ind black. 
may be 
ng guides, 
eophysical 
tunately 
aircraft 
f the 
c) As a data source: There is a need for very small scale imagery to be used 
at the preparatory stage for geological mapping in Canada, particularly at 
scales of 1:250,000. The resolution of ERTS is considered inadequate by 
most geologists for this purpose. Nevertheless some successes are report 
ed, notably by Boydell (this volume). ERTS may be useful to exploration 
groups by providing the kind of information that will define broad targets 
of particular interest, or alternately, allow the quick elminination of 
areas of no interest. ERTS imagery is also an excellent source of infor 
mation on fracture and lineament patterns. 
d) As a source of ideas: ERTS mosaics are being used as a catalyst to pro 
vide the inspiration for new ideas and to promote further thoughts about 
established concepts. 
To indicate something of the variety of ERTS material for study in 
Canada, there follows a selection of images in colour, each accompanied by a 
short description. Two of these accounts are based upon the work of other 
geologists. The description of the Medicine Hat image is from an account 
written by Dr. D. St. Onge of the University of Ottawa. The section on the 
Manicouagan Reservoir was derived from an analysis written by Dr. E. R. Rose 
of the Geological Survey of Canada. 
Figure 4. Eastern Melville Island, Arctic. 1735-19062-4,5,7. 20th July 1974 
This image portrays the atmosphere of the high Arctic. The north mag 
netic pole is less than 80 km away to the east. There are no permanent inhab 
itants in the area which is only visited by the occasional Eskimo hunting 
party. Most of Melville and Byam Martin Island is underlain by thick sand 
stones, siltstones and shales of Middle and Upper Devonian age. The rocks 
are displayed in a series of interlocking dome structures which result from 
folding first on north trending axes followed by folding on E.N.E. trending 
axes. The distinctive white banding represents a quartz sandstone horizon. 
Limestones and sandstones of Permian age underly the northwest projecting 
peninsula of Melville Island. A tenuous distribution of sands and clays of 
Lower Cretaceous age are indicated by a dark grey smear over the folded beds 
in the southern part of Melville. Vegetation is sparse. Limestone and Quartz 
ite areas are usually covered with frost shattered rock fragments (felsenmeer). 
Grasses, sedge and willow are largely restricted to areas of shale and silt- 
stone. 
Figure 5. Manicouagan Reservoir Quebec. 1546-15004-4,5,7. 20th January 1974 
This spectacular circular feature, more than 60 km in diameter, lies with 
in a region of gneiss, intrusives, limestone, quartzite and amphibolite of 
Precambrian age. The lake is an artificial feature produced by the construc 
tion of a dam for hydro-power. Beneath it is preserved a ring of mid-Ordovic 
ian sediments. The interior of the ring is largely occupied by intruded 
andesites in the centre of which there is a single hill composed of anortho 
site older than the andesite. Manicouagan has been variously described as an 
impact crater and as a collapse structure. While shock textures of extra 
terrestrial origin have been discovered in the area, it has also been