408 Mr. Smith on the Stream Works of Pentowan. 



The chief difference to be observed in the strata of the two 

 Pentowan Stream Works, is the want of marine matter in those of 

 the upper. In the lower Stream Work I have described the killas 

 rock, upon which are deposited 5 feet of tin ground, lOf feet of 

 vegetable matter, 24 feet of sea mud, and 3 feet of soil, on a level 

 with which flows the river 54| feet above the solid rock. 



The following notice and sections have also been transmitted to the 

 Society. 



British antiquities (celts, spear's heads, &c.) have been discovered 

 in the Stream Works at the depth of 20, 30, and 10 feet, from 

 whence it appears probable that the greatest part of the accumulation 

 of soil has taken place at a comparatively modern period. 



An accurate representation and description of the Stream Work 

 at Porth in the parish of St. Blazey, of this county, have been pre- 

 sented to the public by Philip Rashleigh, Esq. in the second part of 

 his Description of British Minerals, published in the year 1802. 



Section of the Pentowan Stream Work in 1807. 



Strata. Feet. Inc. 



No. 1. Micaceous sandy clay, interspersed with stones and gravel ... 9 — 



2. Peat, intermixed with roots and leaves 7 — 



3. Sand, in which are found branches and trunks of trees .... 8 — 



4. Finer sand with shells, in which bones, horns, &c. are found .. 12 — 



N. B. The horns are chiefly those of cattle and stags ; a joint of 

 the vertebra of a teWe, and a human skull were likewise found 

 in this stratum, the former is now in the possession of the Rev. 

 John Rogers, of Mawnan, in this county. 



5. Coarse gravel 2 — 



6. Closer sand mixed with clay, with decayed leaves, almost forming 



peat towards the bottom 12 — 



7. Loose stones and gravel 1 — 



8. Tin Ground. 



