PRECARBONIFEROTTS ROCKS OF CH.ARNW00D FOREST. 225 



of each other and of the granite. A little excavation in this wood 

 might bring to light interesting results. 



These are all the dykes with which we are acquainted in the 

 district. Professor Jukes mentions a basaltic dyke in Simpson's 

 pit towards the east end of Mount Sorrel, but for several years all 

 -trace of it has been lost. It will be observed that, except the last 

 described and the Mount-Sorrel felsite, they appear to be rather 

 closely related in character ; and could they have been seen when 

 fresh would probably have then been named either rather felspathic 

 basalts, or andesites poor in silica. 



Probable Outliers of the Cearnwood-Forest Bocks 

 (Narborough District). 



As to the extension of the older rocks of the Forest beneath the 

 Triassic lowlands, we have hitherto known next to nothing, except 

 that syenite is said to have been struck in a boring at Baron Park, 

 6f miles west of Leicester, at a depth of 118 feet. Probably they 

 lie at no very great depth under the Trias of the district to the 

 south, for four or five masses of igneous rock, of a rather similar 

 character, are found rising above the Keuper, in the vicinity of 

 Narborough, sometimes rather boldly, as the syenite does in the 

 Forest region. These occur at the following localities : Enderby, 

 Narborough, Croft Hill, Stony Stanton, with Sapcote and Barrow 

 Hill (see fig. 1). Enderby is about five miles due south from the 

 Groby massif; the next three places lie roughly on a line running 

 for about five miles S.S.W. of it, and the masses of Sapcote, 

 Stony Stanton, and Barrow Hill, not more than one and a half 

 mile apart, are on a line, which, if prolonged to the north, would 

 about pass through Markfield. We have once or twice visited the 

 quarries in these rocks, but have not studied the masses in the same 

 detail as those in the Forest proper. Still, as we have examined, 

 microscopically, specimens from each locality, we maybe able to 

 add something to what is known about them. 



Commencing at Enderby, we found that the prominent knoll on 

 which the village of that name stands consists of igneous rock, in 

 which are sundry excavations ; but the principal quarries are worked 

 in a small, isolated exposure in the lower land south-east of the 

 village, surrounded and almost overlain by Keuper Marl, resting 

 as usual on an irregular surface, and with boulders at the base. The 

 rock here is generally uniform in character, somewhat resem- 

 bling the finer variety of the Groby syenite. It exhibits a 

 compact ground-mass, with numerous small glittering felspar 

 crystals, many of them plagioclase, and a few grains of quartz. 

 Here and there are irregular dull green patches, sometimes half an 

 inch or so in diameter, the smaller of which rather resemble decom- 

 posed hornblende ; the larger, nodes in which much of this mineral 

 is present. The rock, in colour, varies from a dull purphsh or 

 pinkish red to a greyer red (the latter being apparently due to in- 

 cipient decomposition) mottled, as has been said, with dull green. 



