470 
Notices of Memoirs — G. H. Morton. 
Tabular View of tue Carboniferous Limestone and Cefn-y-Fedw Sand- 
stone in the County around Llangollen. 
' Aqueduct Grit, or Upper Sandstone andj 
Conglomerate j 
Upper Skale 
Dee Bridge Sandstone 
Cefn-y-Fedw J Lower Skale witk Fire-clay and bandsi 
Sandstone. ] of Limestone ) 
Middle Sandstone 
Cherty Skale 
Lower Sandstone and Conglomerate 
w Sandy Limestone 
I Upper Grey Limestone 
,, Wkite ,, 
Lower „ ,, 
„ Brown „ 
Feet. 
70 ' 
30 | 
30 J 
18 | 
200 I 
50 f 
250 ! 
75 J 
300 1 
300 1 
120 \ 
480 ) 
Upper 
Cefn-y-Fedw, 
Dee Bridge, or 
Millstone-grit 
Series. 
Middle and Lower 
Cefn-y-Fedw, 
or 
Yoredale 
Series. 
Upper Carboni- 
ferous Limestone. 
Lower ditto. 
1923 
Upper Old Bed Sandstone 300 feet. 
Each of the subdivisions was separately described, and a section 
from the Ty-nant ravine to Tyfyn-uebaf was exhibited, sliowing tbe 
regulär succession of tbe whole of tbe strata from tbe Old Red Sand- 
stone to tbe Coal-measures. Tbe following table sliows tbe gradual 
attenuation of tbe Carboniferous Limestone towards tbe soutli-east. 
Subdivisions. 
Ty-nant. 
Tan-y- 
Castell. 
Trevor 
llocks. 
Bronlieulog. 
Fron. 
Upper Grey Limestone 
300 
300 
250 
66* 
88* 
,, Wkite „ 
300 
250 
140 
99 
27t 
Lower , , , , 
120 
115 
117 
104 
„ Brown ,, 
480 
360 
100 1 
26 1 
1200 
1025 
607 
295 
115 
* Upper portion kas keen denuded. 
t Eeposes on tke Wenloek Skale. 
J Lowest keds not ascertained witk certainty. 
Tbis section shows liow tlie limestone diminisbes in tbickness 
with tbe rise of tbe Wenloek Sbale towards tbe soutli-east. Between 
the Ty-nant ravine and Fron, four miles from tbe former place, tbe 
attenuation is not less than 900 feet. 
Tbe list of fossils collected by tbe autbor contained seventy-seven 
species. Of tbese fifty-eight occur in tbe Upper Grey Limestone, 
and only eigbteen in the Lower Brown Limestone. If the Carboni- 
ferous Limestone is simply divided into Upper and Lower Limestone, 
thirty-eiglit species are peculiar to tbe two upper subdivisions, and 
nineteen to tbe two’ lower subdivisions ; twenty species being com- 
mon to botli. However, tbe species are by no means confined to tbe 
subdivisions in which tliey are found near Llangollen, for tbey 
occur at different horizons in other districts. 
