26 KANSAS ACADEMY OF SCIENCE. 
its point a few small gastropods and other minute shells. The ooze underlying 
the peat consists mostly of minute particles of humus, having a specific gravity 
of 1.016, hence resting but very lightly at the bottom. The shells of dead dia- 
toms, with a small admixture of minute gastropods which at one time lived at 
the surface of the marsh, having greater specific gravity, fall through to the bot- 
tom and form a white stratum several inches in thickness in the course of time. 
This stratum is removed by the wagon load from dried marshes and spread over 
lands as a fertilizer for wheat. It is locally called ‘“‘ marl.’’ I do not know its 
value. 
For the first 25 feet surrounding the lake the marsh is a perfect morass, quite 
dangerous to walk upon, though it may be done; for the next 25 feet it is reas- 
onably safe. It is all unsafe for cattle. This portion of the marsh is sprinkled 
with the common pitcher plant, Sarracenia purpurea. 
Immediately surrounding this first annulus is an annulus 10 to 25 feet wide, 
covered with the same species of marsh grasses and plentifully with Cassandra 
calyculata, Andromeda polifolia, and Kalmia glauca. 
Next outside of this is an annulus about 15 feet wide, covered almost exclu- 
sively with small tamarack trees 3 to 15 feet high. Here the marsh rests upon 
the solid ground. 
The next annulus surrounding the lake is covered with full-grown tamarack 
trees. The width of this ring is 40 to 50 feet, widening to more than double that 
in a pocket between the hills. This strip, although a few inches higher than the 
grassy marsh inside, is usually covered with several inches of water, and is 
known as ‘‘swamp.”’ There is a slight admixturé of clay with the peat here, be- 
ing carried from the neighboring hills. The peat here is composed of sphagnum 
instead of grass, as in the marsh inside. The sphagnum grows plentifully here 
between the roots and knees of the tamarack trees. 
Outside of the tamaracks, next to the hills, there is an interrupted strip of 
black ash swamp, varying from nothing to 50 or 60 feet in width in the pocket 
between the hills. Here there are a few red birch trees, with here and there an 
occasional high-bush cranberry (Viburnum opulus) and clump of high-bush 
huckleberry (Vaccinium ovalifolium). In this part of the swamp the wash 
from the neighboring hills has accumulated somewhat, so that it is almost dry 
except in freshets. Outside of this there are cultivated fields. 
Mart. 
I hold in my hand some samples of mar] taken from a marsh at the head of 
the Shiawassee river, in which the lake has entirely disappeared. The marsh is 
many miles in length; its width at the place observed is nearly half a mile and 
its depth in the center is about seven feet. Recently a large ditch has been dug 
lengthwise through the marsh, cutting down to the clay foundation. Lateral 
ditches have been dug by the people from the side of the marsh to the main 
ditch. Measurements of the depth in one of these laterals, down to the blue clay 
substratum, are as follow: Near outside edge of the marsh, thickness of the 
black muck, 18 inches; underlying white marl, 5 inches; half way between edge 
of the marsh and the big ditch, thickness of the muck, 34 inches; underlying 
marl, 10 inches; thickness near the center of the marsh, of the muck, 444 feet ; 
underlying marl, 32 inches. The muck would probably have been deeper, but 
that at about the time of disappearance of the lake there was deepened drainage, 
causing the center of the marsh to settle down into a dishing shape, leaving the 
outer portion flat, as are all Michigan marshes. 
These three samples of marl were taken from the three localities mentioned as 
