crops are not too small their identification does not offer any diffi-
culties. They have a typical pattern of joints and faults; rather often it
is also possible to observe the bedding planes and foliation, the dip and
the strike of sedimentary and metamorphic rocks.
Till is the most frequent of all surficial deposits, normally covering
more than 50 % of the areas. It may be identified by help of the boul-
ders spread on its surface which are rather easily observed on photos
of scale 1:20 000 or larger. Observation of the boulders is made easien
by the shadows they project. Over vast areas the till has its own mor-
phology. Drumlins are represented by elongated ridges, oriented in the
direction of the ice movement. They are seldom more than one km long
and ten m high and appear in large swarms. Also in such cases when
they are not more than one m high and then very difficult to observe
from the ground, they are easily identified on the air photos. Especially
in mountain valleys the Rogen moraine appears, characterized by ridges
up to thirty — forty m in height, most of them oriented transverse to
the valley (and also the ice movement) direction. The very high num-
ber of big boulders is also typical. The J/eiki moraine consists, when
well-developed, of three elements: plateaus, dead-ice hollows, and so-
called rim ridges on the plateause and in this state offers no identifica-
tion difficulties.
The glacifluvial deposits include quite a few different phenomena.
The eskers are long and sinuous ridges, very often followed on one or
both sides by troughs with small lakes or bogs. Outwash plains usually
have a pattern of braided channels. At the highest marine limit the esk-
ers very often enlarge to a kind of delta. Other deltas or terraces appear
in the mountain areas, where hanging tributary valleys connect with the
main valleys. Very often gravel pits may be observed in the glacifluvial
deposits. When there is forest on them it typically consists of Scotch
pine; it is often quite sparse and gaps are familiar depending on reju-
venation difficulties. Indications showing where glacifluvial sediments
are to be found are given by the thousands of channels eroded by the
meltwater streams from the inland-ice. It is of importance to map such
drainage channels also because they may give hints about the thickness
of the surficial deposits and about rock outcrops. As they cannot have
been formed under a water surface they can give indirect information
about the highest marine limit and the distribution of glacial lakes. The
bearing of this is, that in areas with glacifluvial channels sediments of
the type connected with such waters will not be found.
In connection with the glacifluvial deposits wind deposits occur
frequently. Dunes are long and winding ridges with an oblique cross
profile; "wounds" — often made by reindeers — are common and
expose the very bright shining quarts-sand. Outside the dune-fields
there is often a thin cover of windblown silt not more than one meter
thick, which, however, is very difficult to identify on the air photos.
4