522 F. H. KNOWLTON EVOLUTIOX OF GEOLOGIC CLIMATES 



(Eogersia, Ficophylhim, ProtesspliYllum) which he regarded as belong- 

 ing to this class, but Berry has expressed doubt as to the correctness of 

 this contention, and although they certainly simulate angiospermous 

 plants, it is perhaps best under the circumstances to await further data 

 before definitely accepting or rejecting them. 



As to the probable climatic conditions under which the earliest- 

 Cretaceous plants existed^ Berry says that the "floras are so different 

 in every way from those of the present that it is unsafe to lean too 

 strongly on the facts Avhich may be deduced from the present climatic 

 distribution of the sometimes remotely related representatives of these 

 ancient types in the existing flora." 



It is undoubtedly true that we must approach this matter with a 

 measure of caution, yet a number of undeniable facts seem established. 

 The presence of these floras in Peru, 15° south of the Equator, and in 

 Greenland and Spitzbergen, 78° north, as well as their wide range over 

 both hemispheres, points to relatively uniform and equable conditions, 

 whatever the temperature may have been. The petrified woods sho^- 

 relatively slight seasonal changes, that is, the active growth-ring is very 

 wide and composed of large cellular elements, while the area of restricted 

 growth is very narrow and irregular, and "is as readily explained by a 

 dry season as by a cold winter." Another important fact is that thert} 

 are no certainly known deciduous forms. The size and vigorous growth 

 of most of the vegetation indicates an abundant supply of moisture, weJl 

 distributed throughout most of the annual cycle. Further, if Ave com- 

 pare the several types of plants with their obviously nearest living rela- 

 tives, it seems a fairly reasonable assumption that their temperature 

 requirements could not have been greatly different. Therefore, I feel 

 justified in holding that the climate of early Cretaceous time was equable, 

 moist, and fairly warm, that is^ at least very warm temperate. 



The Barremian of the European scale is believed to be represented in 

 eastern ^orth America by the Arundel formation, which contains a small 

 flora mainly of ferns, cycads, and conifers, but with several of the doubt- 

 ful angiospermous types mentioned as occurring in the Patuxent forma- 

 tion. Of similar age is the so-called Kome flora of Greenland, Avhich 

 includes 88 species, over 40 of which are ferns, Avhile there are 18 coni- 

 fers, 11 cycads, and 3 each in Ginkgo and Equisteum. There are also 

 tAvo undoubted dicotyledons, though there is grave doubt as to their 

 having come from these beds. In the Eastern Hemisphere there has 

 been noted a large flora (23 genera, 45 species) from Portugal, and 

 small floras from England (7 genera, 17 species), France (8 genera, 9 



