Report* and Proceedings — Geological Society of London. 379 



which is to teach the composition and characters of soils and subsoils 

 by means of practical experiments. A list of necessary apparatus is 

 given, and tbe materials for examination should as far as possible be 

 obtained locally. The experiments are adapted to explain porosity 

 and permeability, the formation, of springs, the shrinkage and ex- 

 pansion of clay, the action of lime on certain soils, the temperature 

 of the soil, and the food and growth of plants. The origin of soils 

 in general, of leaf-mould and peat, the action of worms and micro- 

 organisms are discussed, and observations are made on tillage and 

 drainage, on the aspect of the land and the influence of man. It 

 might be mentioned (p. 1) that ground that is hard in dry weather 

 and sticky in wet weather is not necessarily clay, as such conditions 

 maybe found on Chalk tracts. Reference is made (p. 22) to "the 

 foolish man who built his house upon sand"; but this is rightly 

 qualified (pp. 24 and 30) inasmuch as "people prefer to live on 

 a sandy soil rather than on a clay", and the desirable conditions are 

 shown in diagram (fig. 17). The view of "Landslip in the Isle of 

 Wight " (fig. 6) should be "at Lyme Regis ". 



IRIEZF-OIRTS .AJNTID IFIROOIEIEIDIIEsrGrS- 



I. — Geological Society of London. 



June 14, 1911.— Professor W. W. Watts, Sc.D., M.Sc, F.R.S., 

 President, in the Chair. 



The following communications were read : — 



1. "On a Monchiquite Intrusion in the Old Red Sandstone of 

 Monmouthshire." By Professor William S.Boulton, B.Sc, Assoc. R.S.C.,. 

 F.G.S. 



The paper describes a hitherto unrecorded monchiquite, intruded 

 into the Upper Old Red formation of Monmouthshire, about midway 

 between Chepstow and Usk. The precise manner of its intrusion is 

 doubtful ; reasons are given for regarding it either as a dyke with 

 a north-westerly trend or as a volcanic plug (bysmalith). The 

 disturbance and metamorphism of the contact-rocks (seen only at 

 its eastern edge) are dealt with, as also the rounded lumps of marl 

 and subangular blocks and chips of sandstone incorporated in the 

 igneous rock. 



The monchiquite, which is described in detail, contains unusually 

 large phenocrysts (measuring up to 5 and 6 inches) of augite (chrome- 

 diopside) and biotite, generally much corroded. Rounded lumps or 

 ' nodules' of olivine-augite rock with chromite are also included, the 

 olivine now being represented by secondary products, including 

 iddingsite. A second generation of purple idiomorphic augite, biotite, 

 and decomposed olivine occurs porphyritically in the ground-mass, 

 with occasional granules of quartz and chromite. 



The ground-mass is a felt of minute elongated augite prisms, 

 magnetite grains, and flakes of biotite, and the remaining space is 

 occupied by analcite enclosing apatite needles. Reasons are adduced 

 for regarding the analcite of the ground-mass as primary. Ocelli 

 filled with secondary carbonate, chlorite, analcite, etc., are common. 



