310 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION. 



probably is much less. The elements of the earth's 

 orbit for periods of 10 5 0 0 0 years, reckoning backwards 

 from a.d. 1800, are subjoined, from which it will be seen 

 that the axis of rotation of the earth oscillates between 

 certain small limits (4° 51/ 42"), not sufficient to account 

 for the change in the climate of the Arctic regions which 

 the presence of the fossils there appears to involve. 

 Probably the influence of currents, similar to the Gulf 

 stream of the present epoch, may have been instrumental 

 in elevating the temperature of those regions, and pro- 

 ducing a climate which would admit of the existence 

 of Ammonites and plants, which can only flourish in a 

 temperate zone. 



Elements of the Earth's Orbit, according to M. Leverrier. 



Years before 

 1800. 



Excentricity. 



Longitude 



of the 

 Perihelion. 



Inclination. 



Longitude 

 of the Node. 







o / 



O / 11 



o / 



- 100,000 



0-0473 



316 18 



3 45 31 



96 34 



- 90,000 



0-0452 



340 2 



2 42 19 



76 17 



- 80,000 



0-0398 



4 13 



1 18 58 



73 47 



- 70,000 



0-0316 



27 22 



1 13 58 



136 8 



- 60,000 



0-0218 



46 8 



2 36 42 



136 29 



- 50,000 



0-0131 



50 14 



3 40 11 



116 9 



- 40,000 



0-0109 



28 36 



4 3 1 



91 59 



- 30,000 



0-0151 



25 50 



3 41 51 



66 49 



- 20,000 



0-0188 



44 0 



2 44 12 



41 34 



- 10,000 



0-0187 



78 28 



1 24 35. 



16 39 



0 



0-0168 



99 30 



0 0 0 



0 0 



* # * The longitudes are referred to the Ecliptic and Equinox of 1800. 



Mr. James Hall*, the present State Geologist of Iowa, 

 considers that the great development of the lower mem- 



* Mr. James Hall, the author of that magnificent work, the Palaeontology 

 cf the State of New York, &c. &c. 



