Chap. YII.J 
LOWEE LUDLOW ROCKS. 
125 
chief reason for grouping them with the Ludlow rather than with the 
"Wenlock deposit was, that throughout the typical districts of Shropshire 
and Herefordshire these shales occupy the base of the ridges, the harder 
summits and outward slopes of which are composed of Aymestry limestone 
and Upper Ludlow rocks. 
The clearest and finest examples of such physical features are seen in 
ascending from the denuded valley of Wigmore, in which the Wenlock 
shale, d 1 , and limestone, d 2 , are exposed as in the opposite woodcut, and 
thence by a depression in the Lower Ludlow, e\ which ranges into the 
Mary Knoll Dingle and Comus W r ood *, until you reach the stronger stony 
masses of the Aymestry limestone, e 2 , and Upper Ludlow rock, e 3 . 
The inferior strata, e 1 , for the most part argillaceous, are often arranged 
in large spheroidal masses, showing a tendency to concretionary structure, 
which rapidly exfoliate under the atmosphere and break into shivery frag- 
ments. Calcareous nodules, differing only from those of the Wenlock de- 
posit in being usually of a blacker colour, have often been formed round 
an Orthoceras, a Trilobite, or other fossil as a nucleus. 
One of the most prevalent of these organic bodies is our old friend Caly- 
mene Blumenbachii, whose acquaintance the collector may have first made 
in the much lower rocks of Caer Caradoc and Snowdon. (See also Chap. IX.) 
It is accompanied very frequently by the long-tailed Trilobite now called 
Phacops longicaudatus. These two may be considered to be the characteristic 
Trilobites of the formation, though there are several other species ; and 
with them, the Graptolithus priodon (or Ludensis f ), also a Lower Silurian 
fossil, occurs abundantly. The persistence of these typical species clearly 
proves the indivisibility of the Silurian system of life. Nor are Cardiola 
interrupta, PI. XXIII. f. 12, and Murchisonia Lloydii, PI. XXIV. f. 5, less 
characteristic. 
In ascending, the strata become somewhat more sandy, constituting 
thick, earthy, and very slightly calcareous flagstones, the flaglike separation 
being due to laminae of sand. These beds, the ' pendle ' of the workmen, 
were formerly pointed out as being distinguished by containing large Or- 
thoceratites. Recently they have attracted much attention at a spot near 
Leintwardine, and have yielded, to the persevering search of the geo- 
logists of Ludlow and its environs, remains of many Crustacea and abun- 
dance of peculiar Starfishes J. Figures of some of the latter are given at 
p. 127. 
These flaglike strata form the support of the Aymestry or Ludlow lime- 
stone, from which they are usually separated by soft soapy beds, in parts 1 
an imperfect fuller's earth. It is the decomposition of this unctuous 
* Milton passed some time in Ludlow Castle, Ludlow.' 
then a border Welsh fortress, and his 'Mask of J Colonel Colvin of Leintwardine, and Messrs. 
Comus ' was performed in it. Comus Wood is in Lightbody, Cocking, and Marston of Ludlow, have 
one of the deep depressions which vary the surface the merit of these last discoveries. Formerly Mr. 
of the Ludlow promontory. Proctor contributed much from the neighbour- 
t Ludensis is the Latin word signifying ' of hood of Leintwardine. 
