234 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



On each radius of TTC 33-6 (table 164) three growth layers, but 

 not the same three, are sharp. It is quite clear that in a lower forest- 

 border region at least an entire section is necessary to obtain an idea 

 of the variations among growth layers. The reading and interpreta- 

 tion of some sections may even present great difficulties because of the 

 constant contrasts among different radii. 



Branch TTC 33-10 (table 165) was cut off January i, 1943. 



Table 165. — TTC 33-10 



50 cm. 37.5 cm. 24.5 cm. 



1938 I see 



1939 2 see I see 



I psce 

 I sL 



1940 I see 2 see 



I psce 



1941 I see I see i see 



I psce I dL I psL 



1942 2 see 3 see i see 



I sL I dL I psce 



I s iL 



A summary of sections a, at 50 cm., reads : 

 7 see + 3 psce + 2 sL — 5 years. 



Without absolute dating, one would not only be confused by the dif- 

 ferent sequences on different radii, but also he would be helpless to 

 date the growth layers because of the multiplicity involved. On four 

 radii, 90° apart, there are 9, 10, 7, and 9 sharp growth layers. Nine 

 sharp growth layers (7 see + 2 sL) in five years indicate that a sharply 

 bounded growth layer does not necessarily mark the end of a growing 

 season. 



In tree TTC 33 most intra-annuals become sharper inward on the 

 branches. 



TTC 33-ii-a (1938-1942) 

 7 see + I s arc + 2 ddw — 5 years. 



Both 1939 and 1942 have 2 see. 



TTC 33-1 2-a (1939-1942) 



6 see + I psL -f- i dL + 3 ddw — 4 years. 



