174 BULLETIN 109, UNITED STATES NATIONAL MUSEUM. 



parts of the country as to afford almost the Riipply of lime needed 

 for the district" (p. 91). 



Among " recent formations " Mr. Hubbard refers to the singular 

 and extensive "conglomerate" found in Berrien County. "A stra- 

 tum of gravel cemented with lime appears to be very universal 

 throughout this county, at the depth of a few feet, and extensive 

 masses strongly cemented are frequently found exposed in the faces 

 of ravines and banks of streams, appearing like ledges in place." 



On the subject of marl, Mr. Hubbard enters into a well-considered 

 exposition of its nature and uses, and insists upon its great value to 

 the tiller of the soil. Peat is then discussed with similar £oundnea«i 

 of views. Bog iron ore and ocher are cited from numerous localities, 



Mr, Hubbard finally takes up the consideration of the " ancient 

 lake ridge," devoting six pages to the subject. He traces the ridge 

 through eastern Michigan, finds it to have a uniform elevation of 107 

 or 108 feet above Lake Erie, concludes that it was not formed du.ring 

 that turbulent state of waters which brought on the diluvial ma- 

 terials, and proceeds to picture the condition of the country at the 

 time when quiet waters filled the basins of the lakes to the height of 

 the wide-extended lake ridge. He holds that the entire basin of the 

 St. Lawrence and the broad valley of the Mississippi were buried un- 

 der a common inundation, and that it must have been a body of 

 water in direct communication with the ocean. This view necessi- 

 tates the conclusion that the land then lay at a lower level than at 

 present, and a general uplift has been an event of later date. Still, 

 Mr. Hubbard recognizes the evidence that some portions of the inun- 

 dating waters must have been fresh and that they stood at different 

 levels at different epochs. These fluctuations he attributes to the oc- 

 casional destruction of barriers. These views bring out an intel- 

 ligible distinction between the " diluvium " and " alluvium." The 

 former lies next the Tertiary clays and covers the general interior. 

 It is our " Modified drift." The latter is confined to the lower levels 

 near the lakes and is partially stratified. In this occur remains of 

 trees, mastodon, and fresh-water shells. 



Thus three epochs are discriminated : 1. After the elevatory proc- 

 ess had commenced and those erosive actions, transportation, and de- 

 position took place, which we now attribute to drift agencies. 2. A 

 period of pauses and barrier formation, when the " lake alluvions 

 would be forming over the area then occupied by the waters." 3. The 

 era of the present levels. 



Mr. Hubbard's mind, as shown by these early reports, was prone 

 to contemplate geological phenomena in their broader relations. Be- 

 ing now but a young man of 25 years, he gave evidence of excellent 

 capacity for future usefulness in the field of science. 



