REPORT OF THE DIRECTOR AND STA1E GEOLOGIST 1902 r77 



the best stone in the county, both for building purposes and for 

 making lime. 



Following on this is the Salina formation. Jt is GOO or 700 

 feet in thickness and underlies a belt of country 10 to 12 miles 

 in breadth. In the basal portion it is a soft shale, variously 

 colored, disintegrating rapidly when exposed to a clay which 

 might be used for brick. In the upper portion it carries 

 beds of gypsum, succeeded by the Waterlime or Bertie beds. 

 The gypsum beds are worked in the southwestern part of the 

 county, and the Bertie limestone at one place in its southern part. 



Succeeding this in the two extreme towns, is the Onondaga 

 limestone. Like the Bertie it forms fair building material, but 

 owing to its remoteness from a market, is only quarried at one 

 place. 



The distribution of the sand and gravel of the county is ex- 

 tremely irregular. Their occurrence can be only roughly indi- 

 cated by locating the more extensive deposits. These compr : se 

 the Turk hills, partially included in the southeast corner of the 

 county; an area of deposits extending from these hills, north- 

 westward to Irondequoit bay ; mounds and eskers of the Mendon 

 pond region; the Pinnacle hills, w T hich begin southeast of Roches- 

 ter, in Brighton village, and extend along the southern outskirts 

 of the city to the Genesee; a continuation of these which can be 

 traced westward, though less clearly, to Brockport, a distance of 

 18 or 20 miles; an area of sand and gravel hills in the northern 

 part of the town of Chili ; another partially included in the south- 

 western corner of the county; the Ridge road which extends 

 eastward and westward throughout the entire length of the 

 county, passing along the northern outskirts of Rochester; and 

 the beach of Lake Ontario. Besides these are hundreds of smaller 

 deposits scattered over the areas between. 



Of these areas, the material obtained from the Pinnacle 

 range is undoubtedly the best, notably the sand. Much of the 

 gravel in the southern part of the county carries a large ad- 

 mixture of material from the upper calcareous portions of the 

 Salina shale, often amounting to over 50^ of the deposits. It 

 is of interest to note, as pointed out to the writer by Mr E. P. 

 Clapp, of North Rush, that all of the gravel deposits in the 



