42 MICHIGAN SURVEY, 1905. 



The biota of the talus slope, on account of the unstable conditions, is also 

 very poor. Toward the bottom of the slope the rocks become covered by 

 a vegetation of lichens, and farther down by a slight soil and the heath and 

 forest societies. 



As the cliff is destroyed, the talus slope and the top of the ridge tend to 

 approach. The lower part of the talus slope in time becomes broken up 

 to form a soil, and the deciduous forest types from below tend to spread 

 up the slope thus encroaching on the areas occupied by the cliff and talus 

 slope forms. 



IV. Carp River Valley. The sides of the valley of Carp river slope 

 down to a low flood-plain that becomes still lower near the river, grading into 

 mud fiats along the stream. The soil is deep and contains a large amount 

 of organic material, and there is a decrease in its moisture content from 

 the mud flats up into the forest. 



The aquatic biota is a mixture of pond and river types. The mud flats 

 are inhabited by amphibious forms that are replaced on the dryer parts of 

 the flood-plain by the sedge, cassandra, and alder societies, behind which 

 usually occurs a society of Tamarack, White Spruce and White and Black 

 Ash. On the valley slopes occurs the mesophytic forest type of biota. 



The prominent forces at v/ork in these habitats are those of denudation 

 and deposition. The river tends to destroy the adjacent ridges and build 

 up a part of the material derived in this way into mud flats. Deposition 

 during high water builds these flats above the level of the water, and they 

 come in time to form part of the flood-plain. The flood-plain is in turn built 

 up by deposition during floods and by the accumulation of organic remains 

 until the conditions become similar to those in the adjacent forest habitats. 

 The effect of the processes is, therefore, to reduce the country to a level 

 plain thus permitting the encroachment of the forest forms. 



V. VII. Carp and Little Carp Lakes. These lakes on account of the 

 similarity of conditions may be considered together. They are, for the most 

 part, shallow throughout. At the east end of each lake, there is a broad 

 delta formed at the mouth of the entering stream. 



The aquatic biota is of the quiet water type. At the margin occur the 

 amphibious forms that give way on the dryer ground to the flood-plain 

 and forest forms. The deltas afford conditions similar to those on the mud 

 flats and are occupied by a flora of grasses and sedges, and an associated 

 fauna that is characterized by such forms as the snipes, sandpipers, etc. 



The lakes are evidently being filled up, and the conditions are approaching 

 those of the surrounding and encroaching forests. 



VII. 2-S. Little Carp River. This is a small meandering stream which 

 evidently at one time was expanded into a pond by the formation of beaver 

 dams across it. As the Beaver were trapped off, the dams were destroyed 

 and the pond became drained. 



The biota of this stream consists of brook types. The forms on the mud 

 flats along the stream grade into the flood-plain biota which consists princi- 

 pally of grasses and sedges which ordinarily inhabit the wetter parts of the 

 flood-plain, the higher ground types being limited to a narrow zone in front 

 of the forest. 



The changes going on are evidently tending to make the flood-plain dryer, 

 and the forest is encroaching on the meadow. The present extent of the 

 area occupied by the meadow forms is due to the fact that they were able 

 to push in and acquire the territory left by the receding water of the river 

 when the dams were destroyed. 



