THE CLIMATE OF ACADIA IN THE EARLIEST TIMES. 



13 



Sketch Map showing the Distribution op Animals in Lower 

 Ordovician Time. 



7' ^ 



• / 



Areas of Laurentian rocks as in the preceding map. 



Outcrops of the Chazy fauna, found chiefly in limestone rocks, 

 and areas of sandstones supposed to be of that age. Corals and 

 numerous forms of molluscs appeared at this time, and the fauna is 

 supposed to have flourished in shallow, warm seas. 



Outcrops of the Arenig fauna The rocks of this fauna are, 

 to a large extent, mud rocks, with thin flagstones, and the fauna is 

 supposed to indicate the prevalence of colder and deeper waters than 

 those of the Chazy fauna. Since the above map was drawn I have 

 learned that the Arenig fauna has been recognized in the south of 

 France ; if this region were included in the Arenig area, the shaded 

 portion of this map would correspond almost entirely with that of 

 the map on page 11. 



Compare the range of the faunas represented on this sketch- 

 map with those of the preceding. The upper Cambrian faunas 

 are intermediate between the two faunas represented on these maps. 



