Noiice of ihe Peninsula of. Michigan. 307 
‘servations of settlers and surveyors. These earths, I found 
almost uniformly to effervesce with acids, evincing much lime. 
They have quick sand fora basis, at various depths, accord- 
ing to the elevation of the ground. The pebbles and sand 
embraced in the soil are mostly siliceous, with small lumps of 
indurated marl sometimes intermingled. The earth on the 
surface rarely effervesces much with acids, the carbonate of 
lime having been taken up by plants, or decomposed by ve- 
getable acids. Oak openings are at first much less produc- 
tive than heavily timbered land where vegetable mould accu- 
mulates. On dry ground accessible to frequent fires, the 
grasses, leaves, and annual plants are dissipated, leaving a 
jean soil, which is said to improve much under cultivation— 
the roots and plants turned in, decay after the first season, 
and deep ploughing brings to the surface, fertilizing calcare- 
ous earth. In the soil of oak openings, from 15 to 25 bushels to 
the acre of good wheat are procured. For this crop, lime is 
a valuable ingredient in the soil, which might be rendered 
much more productive by ploughing in clover, fostered by 
gypsum. ‘This mineral can be procured at a small expense 
from the south-western part of Sandusky bay, where it has 
been recently discovered of superior quality, in great quanti- 
ty, and of easy access. It is compact, white, and embraces 
considerable gypseous alabaster. 
Rich fresh water shell marl, is of frequent occurrence in 
tamerisk swamps, ponds, and wet basins that were formerly 
ponds, in various parts of the interior. Strata from two to 
five feet in thickness are common in Oakland county, and are 
' constituted almost exclusively of decayed shells. Good lime 
is calcined from this material in pits, with alternate layers of 
wood and marl. It may be advantageously used in agricul- 
ture. Pipe and potters’ clay is found in Oakland county. 
The soil of the hickory openings of the centre and western 
declivity is much superior to that of the eastern oak region. 
The land is generally good from Oakland county to within 
four miles of lake Michigan. 
The oak openings of the southern part of the peninsula are 
represented as superior to the northern division, the soil con- 
taining more clay. ! 
Loose stones, mostly primitive, rest in small quantities on 
the surface in various parts of the interior, rarely more than 
sufficient for the security of wells and cellars. ‘They occur 
on the Chicago road. I noticed large bowlders of granite 
