Eeviews — McHenry and Watts — Rocks and Fossils. 517 



many geologists (whether connected with the Survey or not) who 

 have made a study of Irish Geology, have been consulted in the 

 preparation of the Guide, so that it aims to give a summary of all 

 the leading facts connected with the subject. That this aim has 

 been fully and most carefully carried out, will be acknowledged by 

 all who peruse the work of Messrs. McHenry and Watts. 



At the same time it will be freely conceded, that it is almost 

 impossible to produce a work that will readily serve all the wants 

 of those who have access to the Dublin Collection, and of those who 

 seek only to learn the latest results of enquiry relating to the 

 Geology of Ireland. To get a connected account of each formation 

 we have to look under four headings devoted to each province, and 

 there is no index to facilitate reference. With patience, however, 

 the student will be able to glean what he wants ; and the entire 

 work contains such valuable records of fact and so many lucid 

 explanations and suggestions (all for the small sum of ninepence!), 

 that it should be in the hands of every working geologist. 



The rocks, stratified and igneous, are described in four great 

 groups, those of Leinster, Connaught, Ulster, and Munster. The 

 following are the formations described : — 



Eecbnt Blown Sands, Alluvium, Peat, etc. 



Pleistocene Glacial Drifts. 



Pliocene " ... (" Manui-e Gravels " of Wexford.) 



i Upper Basalts. 

 Eocene or Oligocene \ Leaf Beds, etc. 



( Lower Basalts. 



( Chalk. 

 Cketaceous 1 Upper Greensand. 



Jurassic Lias. 



I Rhsetic Beds. 

 Triassic I Keuper. 



( Bunter. 

 Permian 



/'Coal-measures. 



I Millstone Grit. 



Carboniferous -j Yoredale Series. 



Carboniferous Limestone. 



(Lower Carboniferous (Slate, Sandstone, etc.). 



Old Eed Sandstone { Lower (including Dingle Beds) . 



! Ludlow 

 Wenlock. 

 Tarannon. 

 Llandovery. 

 T CI r Caradoc-Bala. 



Lower Silurian j Llandeilo. 



Cambrian... ■ 



Foliated Crystalline Rocks. 



We observe a certain amount of reticence in assigning any 

 particular age (even a pre-Cambrian age) to the several areas of 

 crystalline schists: and there is justification for caution. While 

 Kinahan, in 1878, remarked that " Eocks older than the Cambrian 

 formation are not known in Ireland" ; Hull, in 1891, observed that 

 " Recent investigations have conclusively established the existence, 

 in several detached areas, of representatives of these [Archaean] 

 the most ancient of known rock-groups." 



