She worked quickly but without hurry. She put an old apron to cover her clothes. In the basement she found a jelly jar with a top and carried it out to the carriage house where the tools were kept. In the chickenyard she caught a little pullet, took it to the block and chopped its head off, and held the writhing neck over the jelly jar until it was half full of blood. Then she carried the quivering pullet to the manure pile and buried it deep. Back in the kitchen she took off the apron and put it in the stove and poked the coals until a flame sprang up on the cloth. She washed her hands and inspected her shoes and stockings and wiped a dark spot from the toe of her right shoe.
(John Steinbeck, East of Eden)
When I encounter the type of structure, I rather feel deep is an adjective – Predicative adjective over the object - than an adverb. Is this right reading?