A piece of rock in which slaty cleavage has been developed, as shown by the fine lines; the coarser bands represent the original bedding planes, now compressed and contorted.

Slaty Cleavage

A piece of rock in which slaty cleavage has been developed, as shown by the fine lines; the coarser…

Dressing slates.

Splitting slates

Dressing slates.

Splitting slates.

Squaring slates

Splitting slates.

"Restoration of Triarthrus Becki, Green, as determined by Beecher from specimens obtained from the Utica Slates (Ordovician), New York. A, dorsal; B, ventral surface. In the latter the single pair of antennae springing up from each side of the camerostome or hypostome or upper lip-lobe are seen. Four pairs of appendages besides these are seen to belong to the cephalic tergum. All the appendages are pediform and bi-ramose; all have a prominent gnathobase, and in all the exopodite carries a comb-like series of secondary processes." — The Encyclopedia Britannica, 1910

Triarthrus

"Restoration of Triarthrus Becki, Green, as determined by Beecher from specimens obtained from the Utica…