580 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
may have been inhabited continuously for a long period, or the habita- 
tion may have been interrupted for certain periods perhaps covering 
several thousand years. In excavating such habitation sites there is 
no possibility of deciding whether objects found together really are 
contemporaneous. In lakes and bogs this is different. Here, con- 
tinuous growth takes place in the shore zones, and every spring a new, 
luxuriant vegetation of swamp plants grows up covering the remains 
left the previous year. At the bottom of the lake one paper-thin 
layer of dead micro-organisms and pulverized plant fragments is de- 
posited upon the preceding, and little by little, as the years pass, the 
lake will be filled up and become a bog. If we imagine a dwelling 
place situated at the shore of such a lake or perhaps somewhere in 
the filled-up bog, the rubbish and the implements left will be placed 
at the proper position within this sequence of layers. Moreover, the 
bog will preserve not only the imperishable flint and the rather re- 
sistant potsherds but also wood and bark, bones, grain, and weed 
seeds. 
The layers of the bog will not only preserve the remains of the 
settlement, but at the same time the peat and lake deposits will yield 
information on the former plant and animal life by their content of 
seeds, bark and twigs, pollen grains, bones, shells, and other organic 
remains. They also provide us with means for dating the layers. For 
such reasons it is of the utmost importance that these deposits are 
thoroughly investigated and above all that the stratigraphy of the 
layers in relation to the habitation remains is established. 
Just as it is important to be able to reconstruct the position of the 
different culture remains in plane and section, it is equally important 
to be able to reconstruct the position of the different deposits which 
surround the culture remains. This is done by measuring the layers 
in the long peat walls which appear during the excavation. The 
excavation is done in sections of half a meter in width from the edge 
of the peat block formed by the trial trenches (drainage trenches). 
When the wall is dug out, it is cut smoothly plane and vertical like 
a well-laid brick wall. In that way we get a clear picture of the 
different layers in the section. It is now a question of using the eyes 
to note the color of the different strata both immediately after the 
cutting of the wall and later when the air has darkened the layers. 
The way in which the deposits dry will also give information about 
the type and structure of the layers. It is important to distinguish 
the strata of the same color and structure to be able to reproduce 
this picture. In practice this is done by drawing vertical lines on 
the wall at a distance of 25 cm. Where these lines cross the horizontal 
layers the intersections are marked by matches put into the wall. 
The intersections are then drawn in a notebook so that all the hori- 
