10 FLORA OF MICHIGAN. 



1,200 feet. In the extreme northwest are ranges which form the copper 

 region ; the central range extends from Keweenaw point across to the Wis- 

 consin line; on either side are the Porcupine mountains and the copper 

 range proper. 



South and east of the copper range lies the iron range of Marquette and 

 Iron counties. The eastern portion of this peninsula is underlaid with 

 stratified rocks belonging to the Silurian period, while the western part is 

 occupied by the copper bearing rocks and those of the Huronian period. 

 Glacial diiit covers deeply a large portion of both the eastern and western 

 sections. 



The Lower Peninsula is generally level or rolling, sloping up in its 

 northern portion to a central ridge or watershed which extends nearly 

 northeast and southwest, the highest part of which, in Otsego county, is 

 1,100 feet above the lake level. 



The shores along the west side of this peninsula are generally bold bluffs 

 which are constantly wearing away, while on the Huron shore they are 

 low and extending by additions* of earth cast up by the waves. 



The rivers are small but their number is great, and these, with the 5,000 

 lakes scattered along the watersheds of the State abundantly water all parts 

 of it. 



Dr. 0. Bominger, a former State Geologist, writes of the geology of the 

 Lower Peninsula as follows: "It forms the center-point of an oceanic bay 

 which seems to have existed without any important alteration in its limits, 

 from the beginning of the Silurian period to the end of the Carboniferous 

 time. We find within the space supposed to have been the bay an uninter- 

 rupted series of marine deposits, following each other in the greatest regu- 

 larity of superposition, which represent all the known formations deposited 

 on this continent from the Silurian period on to the coal formation." 

 The entire surface of th^ peninsula is covered deeply with glacial drift, 

 consisting of sand, gravels and clays variously intermixed. 



The topographical outlines of the Lower Peninsula are due to the joint 

 action of moving ice and flowing water during and following the glacial 

 period. 



Beginning in Presque Isle county the lateral moraine of the Huron gla- 

 cier passes southwest near the line between Montmorency and Alpena 

 counties, thence south by west through Oscoda, Roscommon and Clare, 

 meeting in Me^osta county, the east lateral moraine of Lake Michigan. 

 These join ana pass in a southwest direction through Kent, Barry, Kala- 

 niazoo and St. Joseph counties. The Saginaw bay branch of the Huron 

 glacier unites with the Huron glacier proper, and forms a lateral moraine 

 beginning in Huron county, passing through Sanilac, Lapeer, Oakland, 

 Livingston and portions of Jackson, Washtenaw and Hillsdale counties. 

 This peninsula is divided by these moraines into certain more or less 

 clearly marked floral regions. 



On the map ten regions have been roughly outlined. They are desig- 

 nated by the first ten letters of the alphabet. The following lists of plants 

 are characteristic of the different regions: 



A. SOUTHEASTERN LITTORAL, REGION. 



Acerates viridiflora, Ell. Green Milkweed. 

 Agrimonia parviflora, Ait, Small-flowered Agrimony. 

 Allium Schoenoprasum, L. Chives. 



Castanea sativa, Mill., var. Americana, Gray. Chestnut. 

 Dalibarda repens, LJ. 



