ON THE EREATIC BLOCKS OF ENGLAND, WALES, AND IRELAND. 247 



striae in various directions. They are derived from Markfield, 6 miles N. W. 

 They are syenite, much decomposed by the decay of the felspar, and are 

 about 210 ft. above the sea-level. They were found in making a sewer 

 at a depth of about 4 ft. from the surface, resting upon the Upper Keuper 

 Marl. As they stretched from side to side of the excavation the two 

 large ones had to be blasted to sret them out. The blocks have been 

 removed to the Museum Grounds at Leicester. 



At Knighton, on the estate of Clarendon Park (Ord. Map, 63 N.E.), 

 is a group of boulders. The smallest is 1 ft. 6 in. x 1 ft. 6 in. x 1 ft.; 

 the largest 2 ft. 6 in. x 2 ft. X 2 ft. They are rounded, angular, and 

 subangular. Some of the lower lias blocks are polished, rounded, and 

 striated on both sides. These striations are in various directions. The 

 distances of the rocks from which they were derived are as follows : 

 About 20 miles N.B. for the lias blocks ; 6 miles N.W. for syenites and 

 gi'anites ; 10 miles W. for greenstones. They consist of calcareous grita 

 from the upper beds of lower lias ; granites, syenites, and greenstones are 

 in greatest number. The group is about 300 ft. above the sea-level. The 

 boulders from this locality extend over nearly 100 acres of ground, and 

 some of them have been described in former reports. They have been 

 found in making streets and sewers and digging foundations of houses, 

 lying in upper boulder clay and middle glacial sands. 



In the parish of Thurnby (Ord. map, 63 N.E.) is a large collection 

 of boulders. The smallest is a cube of 1 ft. ; the largest 6 ft. X 2 ft. 

 X 1 ft. 6 in. Many are rounded and subangular. The majority are 

 scratched with shallow scratches on both, sides of the longer face at 

 various angles. They are derived from South Derbyshire, about 40 miles 

 N.W. They are composed of mountain limestone, millstone grit, and 

 permian rocks. The group is about .500 ffc. above the sea-level. The 

 greater portion of these boulders (of whicli there are many thousands 

 under a cubic foot) were turned out in making a tunnel on a new line 

 of railway from Leicester to Melton. An excavation was made in lower 

 boulder clay, which including the tunnel extended about 3 miles. This 

 lower boulder clay was found to be 80 ft. deep in the tunnel-shaft, and rested 

 on the black shales of the middle portion of the lower lias. Boulders 

 have been found in the adjoining villages, and have been described in 

 former reports. 



Shropshire. — The Committee have received from Mr. Luff a valuable 

 report upon the group of erratic blocks found in the neighbourhood of 

 Clun, Shropshire. 



Professor Lapworth has examined a series of specimens, and describes 

 them as Lower Llandovery grits and shales belonging to the Plinlimmon 

 group of central Wales. The hills from which they have been derived are 

 all south of Bala, and situated almost due west from their present position. 



The following are the most remarkable among a large number of. 

 boulders. The ' Great Boundari/ Stone,' marking the boundary of Clun 

 and Treverward townships. It is on Rock Hill, 52° 24' 28" N.L. ; 

 3° 3' 40" W.L., on the estate of Earl Powis. Its dimensions are 

 6 ft. X 6 ft. X 2"5 ft. No striations can be detected, but it is angular 

 and polished on one face. It is a cleaved flagstone, and has travelled 

 from a point south of Machynlleth. It rests upon a bed of clay and rubble 

 above the Upper Ludlow rock. Height above the sea, 1,152 ft. 



The ' Black Hill JBoidder; 52° 24' 40" N.L.; 2° 59' 50" W.L. 



