320 



tlie tertiary clays. These are a fm-mation anterior to both the diluviums 

 and alluvions, and are frequently found extending far beyond the old 

 lake ridge. The country thus underlaid, is that which is almost wholly 

 clothed with a dense growth of timber. This formation wiU be found 

 described under the head of tertiary clays. 



KECENT ALLUVIONS. 



Under this head I shall here allude only to local beds of marl, bog 

 ores, and peat. 



Marl occurs in the greatest abundance, universally distributed though- 

 cut the diluvial district, and consists of local deposits, which originate 

 solely from the lime so profusely contained in the diluviums. Such 

 beds are in constant process of formation and increase, wherever that 

 ingredient exists. As it is present in a much less degree in the ancient 

 alluvion, no extensive beds are consequently found throughout the dis- 

 trict occupied by the latter. 



Bog iron ores are deposits, originating in a similar manner, from the 

 iron contained in the soil, which is dissolved out by the rain waters and 

 collects in low gi'ounds. 



Peat beds are exclusively of vegetable origin, and are common both 

 to the alluvial and diluvial districts. 



The character, abundance, and value of the marl, peat, and bog ore 

 beds of our State, having been fully dwelt upon in the reports of last 

 year, I shall make no further remarks upon their practical applications. 

 I cannot avoid, nevertheless, once again directing the attention of the 

 farmer of Michigan to the fact of the unexampled abundance in which 

 the two former occur, conveniently distributed for universal use as a 

 manure, and urging the use of them, as the cheapest, and in most cases, 

 the best of mineral manures, and which will be found a very important 

 means of improvement in his agricultural economy. 



ORGANIC REMAINS. 



Bones of the Mastodon were last year discovered in the ancient allu- 

 vion, in the western part of Macomb county. They were mostly so 

 much decayed as not to bear exposure to the atmosphere, and a molar 

 tooth only has been preserved. Similar relics were, several years ago, 

 disinterred on the Paw Paw Eiver, in Berrien county. 



